Proliferation Medium Research Articles

Establishment of a Highly Efficient Micropropagation System of Aquilaria crassna Pierre ex Lecomte

Aquilaria crassna Pierre ex Lecomte is a principal species renowned for its production of agarwood. However, the active components of agarwood are not universally in compliance with the standards set by the Chinese Pharmacopoeia. We have identified an elite A. crassna tree with agarotetrol and alcohol extract levels that exceed these standards and have successfully established a stable in vitro micropropagation system using stem segments from this elite tree. The effects of auxins and minerals on axillary-bud induction, shoot multiplication, and rooting were investigated. The most effective medium for axillary-bud induction was a half-strength Murashige and Skoog (1/2MS) medium supplemented with 0.50 mg/L 6-benzylaminopurine (6-BA), achieving an induction rate of 53.33% with minimal hyperhydricity. The optimal shoot proliferation medium was an MS medium with 0.40 mg/L 6-BA, yielding a propagation coefficient of 2.96 without hyperhydricity. The best rooting medium comprised quarter-strength MS (1/4MS) macroelements and 1/2MS microelements with 0.10 mg/L naphthaleneacetic acid (NAA), resulting in an 82.54% rooting rate. Substrate effects on transplant survival and growth were also evaluated, and peat soil was identified as the best substrate, achieving a survival rate of 96.67%. This study introduces a straightforward and efficient in vitro micropropagation system utilizing mature A. crassna as explants. It holds significant importance for the consistent production of agarwood that complies with the standards of the Chinese Pharmacopoeia and provides a model for the targeted breeding of medicinal plants.

In vitro cluster buds regeneration and control of shoot tip necrosis in tissue cultures of Trichosanthes cucumerina L.

Trichosanthes cucumerina L. is a medicinal vine with great potential that can be used as a vegetable. In this study, an efficient in vitro regeneration system of T. cucumerina was established by inducing adventitious buds and controlling Shoot Tip Necrosis (STN) in the in vitro culture. The results of hormone single factor and orthogonal experiments showed that 6-BA had a significant effect on inducing adventitious buds. The best medium for bud proliferation was MS + 6-BA 3.0 mg·L− 1 + KIN 2.0 mg·L− 1 + NAA 0.5 mg·L− 1, and the proliferation capacity was 14.68. However, after three consecutive subcultures, a higher incidence of STN (78.86%) was observed. The results of the STN control experiment showed that reducing the concentration of inorganic salt, shortening the subculture interval, and increasing the Ca2+ in the medium could effectively control the occurrence of STN. However, reducing the concentration of inorganic salt and shortening the subculture interval excessively reduces the proliferation capacity significantly. Considering both the incidence of STN and proliferation capacity, the measures proposed in this study to alleviate STN were to keep the concentration of inorganic salt unchanged, adjust the subculture interval from 45 days to 40 days, and increase the Ca2+ concentration in the medium to 480 mg·L− 1. When the subculture interval was 40 d, the stem segments obtained the lowest STN incidence (8.3%) and higher shoot proliferation capacity (10.02) on the medium of MS + 3.0 mg·L− 1 6-BA + 2.0 mg·L− 1 KIN + 0.5 mg·L− 1 NAA + 360.36 mg·L− 1 Ca2+ (360 mg·L− 1 is the concentration of additional calcium to be added, and after this addition, the total calcium concentration in the MS medium was 480.48 mg·L− 1). The best rooting medium for stem segments was MS + 0.50 mg·L− 1 NAA; the rooting rate was 100%, and no STN occurred. After acclimation, the survival rate of the rooted plantlet reached 95% after 40 days in the soil matrix of coconut husk: humus soil: perlite = 2: 2: 1 (v/v). The results of this study not only reveal the mechanism of STN in T. cucumerina, but also provide technical support and a theoretical basis for its further breeding and cultivation.

Induction and Suspension Culture of Panax japonicus Callus Tissue for the Production of Secondary Metabolic Active Substances.

Using Panax japonicus as research material, callus induction and culture were carried out, and high-yielding cell lines were screened to establish a suspension culture system that promotes callus growth and the accumulation of the "total saponins" (total content of triterpenoid glycosides or ginsenosides). Using the root as an explant, the medium for callus induction and proliferation was optimized by adjusting culture conditions (initial inoculation amount, carbon source, shaking speed, hormone concentration, culture time) and a high-yielding cell line with efficient proliferation and high total saponins content was screened out. The conditions of suspension culture were refined to find out the most suitable conditions for the suspension culture of callus, and finally, the suspension culture system was established. We found that the lowest (5%) contamination rate was achieved by disinfecting the fresh roots with 75% alcohol for 60 s, followed by soaking in 10% NaClO for 15 min. The highest induction rate (88.17%) of callus was obtained using the medium MS + 16.11 μmol·L-1 NAA + 13.32 μmol·L-1 6-BA + 30.0 g·L-1 sucrose + 7.5 g·L-1 agar. The callus was loose when the callus subcultured on the proliferation medium (MS + 5.37 μmol·L-1 NAA + 13.32 μmol·L-1 6-BA + 30.0 g·L-1 sucrose + 3.8 g·L-1 gellan gum) for 21 days. The callus growth was cultured in a liquid growth medium (MS + 5.37 μmol·L-1 NAA + 13.32 μmol·L-1 6-BA + 30.0 g·L-1 sucrose) with an initial inoculation amount of 40 g·L-1, a shaking speed of 110 r/min and darkness. Cell growth was fastest with a culture period of 21 days. We replaced the growth medium with the production medium (MS + 5.37 μmol·L-1 NAA + 13.32 μmol·L-1 6-BA + 30.0 g·L-1 glucose) for maximum accumulation of total saponins. [Conclusion] A callus induction and suspension culture system for the root of P. japonicus was established. In this way, we can promote the accumulation of total saponins in callus cells and provide a basis for large-scale cell culture and industrial production of medicinal total saponins.

Research on the rapid tissue breeding technology of the endangered plant Cibotium barometz (L.) J. Sm.

Cibotium barometz (L.) J. Sm., a fern, holds significant value in traditional Chinese medicine. This research aimed to establish a rapid tissue breeding technology for Cibotium barometz (L.) and provide a theoretical basis for its artificial breeding and industrial planting. The optimum conditions for spores germination were selected, including both the best sterilization time and the ideal spore germination medium. Subsequently, the optimal medium for proliferation and differentiation were chosen, and the optimal concentration of plant hormones was screened to determine the optimal medium. The rooting experiment was performed in two single-factor experiments by using differentiated sporophytes as materials. These experiments showed that the optimal sterilization time was 11 min and the best medium for germination was 1/8MS + 0.02 mg/L IAA. MS medium was suitable for proliferation, while WPM medium was suitable for sporophyte differentiation. The best medium for growth was MS + 1.0 mg/L IAA + 0.5 mg/L 6-BA. In the absence of sucrose, the seedlings barely grew and failed to differentiate into sporophytes. They showed optimal growth and differentiation at a sucrose concentration of 20 g/L. The plant growth regulators plant growth regulators used, including IAA, NAA, 6-BA, and GA3, showed more effective differentiation, wherease KT had a slightly weaker effect. The rooting rate reached the maximum when the concentrations of ABT and IBA were at 1.5 mg•L− 1 and IAA was at 1.0 mg•L− 1. The IBA had a significant effect on the average and the longest root length, while the three PGRs had no obvious effect on the average or maximum diameter. Plant tissue culture seedlings still have good genetic stability after subsequent generation. In this study, the optimal cultivation conditions for rapid breeding technology in tissue culture, covering stages from germination and growth to differentiation and rooting, were obtained. Moreover, sporophytes were successfully transplanted to the external environment. This study provided a theoretical reference for the industrial planting of C. barometz.

Manufacturing of 3D-Printed Hybrid Scaffolds with Polyelectrolyte Multilayer Coating in Static and Dynamic Culture Conditions.

Three-dimensional printing (3DP) has emerged as a promising method for creating intricate scaffold designs. This study assessed three 3DP scaffold designs fabricated using biodegradable poly(lactic) acid (PLA) through fused deposition modelling (FDM): mesh, two channels (2C), and four channels (4C). To address the limitations of PLA, such as hydrophobic properties and poor cell attachment, a post-fabrication modification technique employing Polyelectrolyte Multilayers (PEMs) coating was implemented. The scaffolds underwent aminolysis followed by coating with SiCHA nanopowders dispersed in hyaluronic acid and collagen type I, and finally crosslinked the outermost coated layers with EDC/NHS solution to complete the hybrid scaffold production. The study employed rotating wall vessels (RWVs) to investigate how simulating microgravity affects cell proliferation and differentiation. Human mesenchymal stem cells (hMSCs) cultured on these scaffolds using proliferation medium (PM) and osteogenic media (OM), subjected to static (TCP) and dynamic (RWVs) conditions for 21 days, revealed superior performance of 4C hybrid scaffolds, particularly in OM. Compared to commercial hydroxyapatite scaffolds, these hybrid scaffolds demonstrated enhanced cell activity and survival. The pre-vascularisation concept on 4C hybrid scaffolds showed the proliferation of both HUVECs and hMSCs throughout the scaffolds, with a positive expression of osteogenic and angiogenic markers at the early stages.

In Vitro Propagation Technology for the Endangered Aquatic Species Nymphoides coronata.

Nymphoides coronata is an endangered aquatic plant species with significant medicinal and ecological importance. To preserve N. coronata from going extinct, we need to provide seedlings and efficient multiplication techniques so that it can be extensively studied. This study aimed to identify the most suitable sterilization treatment, growth medium, and substrate for the cultivation and propagation of N. coronata. Ethanol sterilization, fungicide treatment, and sterile water washing were the most important sterilization steps. A combination of 6-benzylaminopurine (6-BA) and indoleacetic acid (IAA) was the most suitable medium for bud induction and shoot proliferation. The use of α-naphthaleneacetic acid (NAA) increased the rooting rate and rooting time compared to indole-3-butyric acid (IBA). Increasing the concentration of NAA from 0.5 to 1.0 mg/L increased the rooting rate from 78 to 100% and reduced the rooting time from 7 to 5 days. The survival rate of N. coronata seedlings was 100% in a mixture of red soil and sand (1:1, w/w). As a result, the procedure mentioned above could potentially be used to safely propagate this rare species on a large scale. These findings provide valuable insights into the optimal conditions for the successful cultivation and propagation of N. coronata, which can contribute to the conservation and sustainable use of this important rare plant species.

Computer-assisted engineering of stable human leukemia inhibitory factor

Due to their capacity for long-term expansion and differentiation potential, embryonic stem cells (ESC) can be selected as seed cells for generating cultured meat. Leukemia inhibitory factor (LIF) is a pleiotropic cytokine with a wide range of activities, including maintaining ESC in a totipotent state in vitro, which is an essential additive component of the ESC proliferation medium. However, owing to the low thermal stability of wide-type human LIF (hLIF-WT), the cost was increased by repeatedly added and storage loss. Here, we tackle this problem using a computer-assisted protein engineering strategy to create a unique modified hLIF with three mutations displaying unprecedented stability and enhanced biological function. The molecule holds considerable promise for stem cell research and the cultured meat field.

Crusting-fabricated three-dimensional soy-based scaffolds for cultured meat production: A preliminary study

Crusting has been developed as a non-chemical and non-machine intensive scaffold fabrication method. This method is based on the self-assembling ability of soy biomolecules, allowing the fabrication of a three-dimensional network for cell growth. Preliminary characterization revealed differences in pore size, water absorption, and degradation between pure soy-based scaffold (Y2R) and with added glycerol (Y2G). The Fourier-transform infrared spectrum absorbance peaks of functional groups related to proteins, carbohydrates, and lipids hinted the integration of soy biomolecules potentially via the Maillard reaction, as supported by the visible browning of the scaffold surface. Microscopic images revealed aligned myotubes in both scaffolds, with Y2G myotubes having greater proximity after 72 h of proliferation. Both spontaneous and electro-stimulated contractions were recorded as early as 72 h in proliferation medium. Crusting-fabricated soy-based scaffolds can further be explored for its application in cultured meat production.

Periodic static compression of micro-strain pattern regulates endochondral bone formation.

Introduction: Developmental engineering based on endochondral ossification has been proposed as a potential strategy for repairing of critical bone defects. Bone development is driven by growth plate-mediated endochondral ossification. Under physiological conditions, growth plate chondrocytes undergo compressive forces characterized by micro-mechanics, but the regulatory effect of micro-mechanical loading on endochondral bone formation has not been investigated. Methods: In this study, a periodic static compression (PSC) model characterized by micro-strain (with 0.5% strain) was designed to clarify the effects of biochemical/mechanical cues on endochondral bone formation. Hydrogel scaffolds loaded with bone marrow mesenchymal stem cells (BMSCs) were incubated in proliferation medium or chondrogenic medium, and PSC was performed continuously for 14 or 28days. Subsequently, the scaffold pretreated for 28days was implanted into rat femoral muscle pouches and femoral condylar defect sites. The chondrogenesis and bone defect repair were evaluated 4 or 10weeks post-operation. Results: The results showed that PSC stimulation for 14days significantly increased the number of COL II positive cells in proliferation medium. However, the chondrogenic efficiency of BMSCs was significantly improved in chondrogenic medium, with or without PSC application. The induced chondrocytes (ichondrocytes) spontaneously underwent hypertrophy and maturation, but long-term mechanical stimulation (loading for 28days) significantly inhibited hypertrophy and mineralization in ichondrocytes. In the heterotopic ossification model, no chondrocytes were found and no significant difference in terms of mineral deposition in each group; However, 4weeks after implantation into the femoral defect site, all scaffolds that were subjected to biochemical/mechanical cues, either solely or synergistically, showed typical chondrocytes and endochondral bone formation. In addition, simultaneous biochemical induction/mechanical loading significantly accelerated the bone regeneration. Discussion: Our findings suggest that microstrain mechanics, biochemical cues, and in vivo microenvironment synergistically regulate the differentiation fate of BMSCs. Meanwhile, this study shows the potential of micro-strain mechanics in the treatment of critical bone defects.

A matter of differentiation: equine enteroids as a model for the in vivo intestinal epithelium

Epithelial damage due to gastrointestinal disorders frequently causes severe disease in horses. To study the underlying pathophysiological processes, we aimed to establish equine jejunum and colon enteroids (eqJE, eqCE) mimicking the in vivo epithelium. Therefore, enteroids were cultivated in four different media for differentiation and subsequently characterized histomorphologically, on mRNA and on protein level in comparison to the native epithelium of the same donor horses to identify ideal culture conditions for an in vitro model system. With increasing enterocyte differentiation, the enteroids showed a reduced growth rate as well as a predominantly spherical morphology and less budding compared to enteroids in proliferation medium. Combined or individual withdrawal of stem cell niche pathway components resulted in lower mRNA expression levels of stem cell markers and concomitant differentiation of enterocytes, goblet cells and enteroendocrine cells. For eqCE, withdrawal of Wnt alone was sufficient for the generation of differentiated enterocytes with a close resemblance to the in vivo epithelium. Combined removal of Wnt, R-spondin and Noggin and the addition of DAPT stimulated differentiation of eqJE at a similar level as the in vivo epithelium, particularly with regard to enterocytes. In summary, we successfully defined a medium composition that promotes the formation of eqJE and eqCE consisting of multiple cell types and resembling the in vivo epithelium. Our findings emphasize the importance of adapting culture conditions to the respective species and the intestinal segment. This in vitro model will be used to investigate the pathological mechanisms underlying equine gastrointestinal disorders in future studies.

Developmental regulation of zinc homeostasis in differentiating oligodendrocytes

Oligodendrocytes develop through sequential stages and understanding pathways regulating their differentiation remains an important area of investigation. Zinc is required for the function of enzymes, proteins and transcription factors, including those important in myelination and mitosis. Our previous studies using the ratiometric zinc sensor chromis-1 demonstrated a reduction in intracellular free zinc concentrations in mature MBP+ oligodendrocytes compared with earlier stages (Bourassa et al., 2018). We performed a more detailed developmental study to better understand the temporal course of zinc homeostasis across the oligodendrocyte lineage. Using chromis-1, we found a transient increase in free zinc after O4+,O1− pre-oligodendrocytes were switched from proliferation medium into terminal differentiation medium. To gather other evidence for dynamic regulation of free zinc during oligodendrocyte development, qPCR was used to evaluate mRNA expression of major zinc storage proteins metallothioneins (MTs) and metal regulatory transcription factor 1 (MTF1), which controls expression of MTs. MT1, MT2 and MTF1 mRNAs were increased several fold in mature oligodendrocytes compared to oligodendrocytes in proliferation medium. To assess the depth of the zinc buffer, we assayed zinc release from intracellular stores using the oxidizing thiol reagent 2,2′-dithiodipyridine (DTDP). Exposure to DTDP resulted in ∼ 100% increase in free zinc in pre-oligodendrocytes but, paradoxically more modest ∼ 60% increase in mature oligodendrocytes despite increased expression of MTs. These results suggest that zinc homeostasis is regulated during oligodendrocyte development, that oligodendrocytes are a useful model for studying zinc homeostasis in the central nervous system, and that regulation of zinc homeostasis may be important in oligodendrocyte differentiation.

Response of various carbon sources for in vitro culture establishment and shoot proliferation of banana cv. Chinichampa (AAB) through shoot tip

Bananas are one of the most important tropical fruits in the world market, a significant staple food and a major export commodity. In vitro propagated banana plants are steadily becoming the planting material of choice because of disease free, uniformity and the possibility of rapid multiplication. The present investigation was carried out at the tissue culture laboratory, Department of Horticulture, School of Agricultural Sciences, Nagaland University, Medziphema campus during the year 2019-2022. Data recorded for different parameters viz. days to greening, days required for multiple buds’ initiation, number of multiple buds produced per explant and length of multiple buds after 30 days were subjected to completely randomized design (CRD). The present study revealed the importance of various carbon sources and its role in micropropagation of banana through shoot tip culture. The minimum day to greening, multiple buds initiation and maximum length of multiple buds was observed in shoot proliferation medium supplemented (SPM S) with 30g sucrose. The highest number of multiple buds was recorded in shoot proliferation medium supplemented with 30g table sugar. The results indicate the significance of sucrose as carbon sources in micropropagation of banana. They improved plant regeneration and facilitated rapid multiplication of disease and virus free banana plantlets.

Osteogenically committed hUCMSCs-derived exosomes promote the recovery of critical-sized bone defects with enhanced osteogenic properties.

Low viability of seed cells and the concern about biosafety restrict the application of cell-based tissue-engineered bone (TEB). Exosomes that bear similar bioactivities to donor cells display strong stability and low immunogenicity. Human umbilical cord mesenchymal stem cells-derived exosomes (hUCMSCs-Exos) show therapeutic efficacy in various diseases. However, little is known whether hUCMSCs-Exos can be used to construct TEB to repair bone defects. Herein, PM-Exos and OM-Exos were separately harvested from hUCMSCs which were cultured in proliferation medium (PM) or osteogenic induction medium (OM). A series of in-vitro studies were performed to evaluate the bioactivities of human bone marrow mesenchymal stem cells (hBMSCs) when co-cultured with PM-Exos or OM-Exos. Differential microRNAs (miRNAs) between PM-Exos and OM-Exos were sequenced and analyzed. Furthermore, PM-Exos and OM-Exos were incorporated in 3D printed tricalcium phosphate scaffolds to build TEBs for the repair of critical-sized calvarial bone defects in rats. Results showed that PM-Exos and OM-Exos bore similar morphology and size. They expressed representative surface markers of exosomes and could be internalized by hBMSCs to promote cellular migration and proliferation. OM-Exos outweighed PM-Exos in accelerating the osteogenic differentiation of hBMSCs, which might be attributed to the differentially expressed miRNAs. Furthermore, OM-Exos sustainably released from the scaffolds, and the resultant TEB showed a better reparative outcome than that of the PM-Exos group. Our study found that exosomes isolated from osteogenically committed hUCMSCs prominently facilitated the osteogenic differentiation of hBMSCs. TEB grafts functionalized by OM-Exos bear a promising application potential for the repair of large bone defects.

DEVELOPMENT OF A PERSONALIZED HUMAN PANETH CELL MODEL USING INTESTINAL ORGANOIDS

Abstract INTRODUCTION Paneth cells are a specialized intestinal epithelial cell subtype whose major function is to produce antimicrobial peptides (AMPs). Alterations in Paneth cell function are associated with Crohn’s disease (CD) but the confounding influences of environmental factors and/or genetic variations makes it difficult to identify the cause of this. Human intestinal organoid (HIO) technology now allows for the generation of intestinal epithelium from any individual but there are relatively few protocols that allow for the enrichment of Paneth cells within organoids. Our goal was to specifically enrich the Paneth cell population in HIOs derived from induced pluripotent stem cells (iPSCs). METHODS iPSCs from a control individual and 2 CD patients were directed to HIOs and then dissociated to generate purified populations of epithelial only-HIOs (eHIOs). eHIOs were passaged weekly in proliferation medium (EGF, Noggin and CHIR99021) and the γ-secretase inhibitor, DAPT, was added to direct towards a Paneth cell fate. Flow cytometry, qPCR and immunocytochemistry were used to determine Paneth cell numbers, and gene and protein expression of various AMPs respectively. RESULTS iPSC-derived eHIOs from the control individual, which were used to develop this enrichment protocol, could be maintained for at least 4 months in proliferation medium. Flow cytometry analysis of the Paneth marker lysozyme revealed that the population of Paneth cells in eHIOs significantly increased from ~1% in proliferation media to ~28% upon treatment with DAPT. qPCR analysis demonstrated that DAPT treatment significantly increased the expression of the Paneth cell associated genes DEFA5, DEFA6, ITLN2, REG3A and PLA2G2A. Immunocytochemistry revealed that DAPT treated eHIOs were enriched for cells possessing granulated lysozyme, and also for additional AMPs such as DEFA5, ITLN2 and REG3A. The presence of the bacterial sensors TLR2, TLR5 and NOD2 were also detected in our Paneth cells. Finally, to confirm the applicability to CD patients, we applied our protocol and found the population of Paneth cells in CD eHIOs significantly increased from ~1% in proliferation media to ~10% upon treatment with DAPT, had significantly increased expression of the Paneth cell related genes and were also were enriched for cells with granulated AMPs. CONCLUSION We have successfully developed a methodology to enrich Paneth cells in iPSC-derived HIOs from both healthy and CD patients. Given that iPSCs can be generated from donor cells stored in well characterized biorepositories or obtained from a small blood draw from any CD patient, this modeling system now opens up a new avenue of research by allowing an examination of how environmental factors (microbes/cytokines) and/or genetic variations influence human Paneth cell function in a personalized manner. Fluorescent image showing the presence of granulated DEFA5 (green) in E-cadherin+ (red) human iPSC-derived intestinal organoids treated with DAPT (X60). qPCR analysis of Paneth cell related genes in proliferation media compared to DAPT treatment. *P < .05, **P < .01, ***P < .001, and ****P < .0001 as compared to gene expression in proliferation media.

Green Globular Body Induction and Plantlet Regeneration of Endangered Fern Adiantum reniforme var. sinense

Background: Adiantum reniforme var. sinense is a pteridophyte with considerable ornamental importance and medicinal value. However, the wild population of A. reniforme var. sinense has gradually become scarce due to sparse distribution and human activities. Green Globular Bodies (GGBs) are specific tissue which use to propagate ferns in vitro. The study uses GGBs induced from sporophytic embryos to preserve and to proliferate this pteridophyte. Methods: The present study was carried out during year 2018-2020 at National Ilan University. The developing sporophyte of Adiantum reniforme var. sinense were used to induce GGBs. The optimal medium for GGBs proliferation and differentiation in terms of basal salts, plant growth regulators, sugar concentrations and gelling agents was examined. The structure of GGBs and the embryos were analyzed by paraffin section as well. Result: The result indicates the 100% GGBs induction rate from sporophytic embryos for the first time could be obtained under BA (0.1 mg L-1) and NAA (0.15 mg L-1). For subsequent proliferation of GGBs required a higher concentration of NAA (10 mg L-1). Cytokinins such BA, KT and TDZ, inhibited GGBs proliferation. In vitro optimal amount of basal salts, plant growth regulators, sugar concentrations and gelling agents for GGB proliferation were obtained as 2 g L-1 Hyponex, 10 mg L-1 NAA, 15 g L-1 sucrose and 4 g L-1 gelrite, respectively. Paraffin sections revealed histological characteristics of the sporophytic embryo and GGB.

Establishment of an In Vitro Micropropagation Protocol for Hibiscus moscheutos L. ‘Berry Awesome’

Hibiscus moscheutos L. ‘Berry Awesome’ is a complex hybrid of the new Proven Winners Summerific series of varieties with highly ornamental characteristics. Micropropagation of highly ornamental varieties is important for mass production of planting material for commercial purposes. The traditional methods for propagating Hibiscus varieties, such as cuttings or seed propagation, however, do not guarantee high rates of production of high-quality seedlings. To solve this problem, an attempt was made to develop protocols for micropropagation of Hibiscus moscheutos L. ‘Berry Awesome’ in vitro on agar and liquid medium using a bioreactor system, followed by ex vitro adaptation of the regenerants. The optimal method for sterilization of nodal explants as well as the optimal composition of the initiation medium for shoot proliferation and rooting were determined. For micropropagation on a liquid medium, a rocker-type bioreactor was used, and its advantages over micropropagation on an agar medium were demonstrated. The results showed that the best sterilization method for nodal segment explants was as follows: pretreatment by rinsing with running tap water, sterile water, and distilled water for 70 min and soaking for 5 min in a mixture of solutions of ethyl alcohol (96%), hydrogen peroxide (38%), and water in a ratio of 1:1:2. In this case, live and sterile explants accounted for 62.6%. The optimal initiation medium for axillary buds in nodal segments was the Murashige and Skoog (MS) medium supplemented with 0.1 mg L−1 N-(2-chloro-4-pyridinyl)-N’-phenylurea (CPPU), which resulted in 73.3% of axillary buds being induced. The optimal solid proliferation medium was MS medium supplemented with 0.1 mg L−1 CPPU with a proliferation coefficient of 5.8. In a liquid medium, the optimal concentration of CPPU was 0.05 mg L−1 with a proliferation coefficient of 9.2. The best medium for rooting/shoots with agar and in bioreactors was MS medium with the addition of 0.1 mg L−1 indole-3-butyric acid (IBA). The highest rooting rate was 99.0% in both types of media, and the survival rate of plantlets was 88.7% in solid media and 98.7% in the bioreactor.

Effect of Arabinogalactans on Induction of White-Opaque Somatic Embryos of Avocado (Persea americana Mill.) cv. Duke-7.

The development of somatic embryogenesis in avocado (Persea americana Mill.) has been hampered by different chronic problems. One such problem is the low level of induction of white-opaque somatic embryos (WOSEs) during the process of obtaining full avocado plants. We detected the induction of multiple WOSEs promoted after the placement of three or four small WOSEs over the embryogenic callus of Duke-7. Among the other possible chemical inductors of the Arabinogalactans (AGPs), we identified a family of extracellular plant proteoglycans implicated in many aspects of the in vitro induction of somatic embryos (SE). We extracted AGPs directly from embryogenic cultures of avocado. When the induction/proliferation medium of embryogenic avocado calli (MS-0.1 mg L-1 Picloram) was supplemented with 1-2 mg L-1 AGP, the induction rate of good-quality WOSEs from the embryogenic callus increased significantly (more than ten times that of the control without AGP) and this effect persisted for at least five subcultures after the initial treatment with AGP. AGP also modified the texture and quality of the callus. The effect of AGP extends to other cultivars and proliferation media. Our objectives were to improve the induction of WOSEs and study the effect of AGP in the somatic embryogenesis of avocado.

Hypoxia enhances human myoblast differentiation: involvement of HIF1α and impact of DUX4, the FSHD causal gene

BackgroundHypoxia is known to modify skeletal muscle biological functions and muscle regeneration. However, the mechanisms underlying the effects of hypoxia on human myoblast differentiation remain unclear. The hypoxic response pathway is of particular interest in patients with hereditary muscular dystrophies since many present respiratory impairment and muscle regeneration defects. For example, an altered hypoxia response characterizes the muscles of patients with facioscapulohumeral dystrophy (FSHD).MethodsWe examined the impact of hypoxia on the differentiation of human immortalized myoblasts (LHCN-M2) cultured in normoxia (PO2: 21%) or hypoxia (PO2: 1%). Cells were grown in proliferation (myoblasts) or differentiation medium for 2 (myocytes) or 4 days (myotubes). We evaluated proliferation rate by EdU incorporation, used myogenin-positive nuclei as a differentiation marker for myocytes, and determined the fusion index and myosin heavy chain-positive area in myotubes. The contribution of HIF1α was studied by gain (CoCl2) and loss (siRNAs) of function experiments. We further examined hypoxia in LHCN-M2-iDUX4 myoblasts with inducible expression of DUX4, the transcription factor underlying FSHD pathology.ResultsWe found that the hypoxic response did not impact myoblast proliferation but activated precocious myogenic differentiation and that HIF1α was critical for this process. Hypoxia also enhanced the late differentiation of human myocytes, but in an HIF1α-independent manner. Interestingly, the impact of hypoxia on muscle cell proliferation was influenced by dexamethasone. In the FSHD pathological context, DUX4 suppressed HIF1α-mediated precocious muscle differentiation.ConclusionHypoxia stimulates myogenic differentiation in healthy myoblasts, with HIF1α-dependent early steps. In FSHD, DUX4-HIF1α interplay indicates a novel mechanism by which DUX4 could interfere with HIF1α function in the myogenic program and therefore with FSHD muscle performance and regeneration.

Effect of culture filtrates of Fusarium fungi on oat callus cultures

The effect of three concentrations (30, 40 and 50%) of the culture filtrate (CF) of the genus Fusarium fungi (F. sporotrichioides, F. poae, F. equiseti, F. oxysporum) on the growth and development parameters of oat callus culture was evaluated. CF at the callus proliferation stage was used to select somaclonal cell lines with mycotoxin tolerance traits. Prior to this, callusogenesis induction was carried out on the Murashige-Skoog (MS) medium with 3 mg/l 2,4-D and 2 mg/l UIC in the culture of immature embryos of the Tyumensky Golozerny, Tubinsky, Zolotoy Pochatok and Talisman varieties. The material for the experiment was selected from the ears of the plants grown in the summer period of 2016–2018 on the experimental fields in the Krasnoyarsk forest-steppe. Callus size was recorded when transplanted onto the proliferation media (MS + 1.5 mg/l 2,4-D), control and CF-containing media. After 30 days of cultivation, callus growth, signs of necrosis and organogenesis were noted. At the end of the experiment, the number of the regenerants formed was counted. The presence of CF in the proliferation medium already at a concentration of 40% provided a decrease in the proliferative activity and increased the frequency of necrosis by at least 50%. Similar results were obtained at the CF level of 50%. On the media with F. poae CF, the reduction of callus viability reached 60–70%. The calluses that remained viable under these conditions had a frequency of regenerant formation and organogenesis 2–3 times higher than the samples that were not influenced by the selective factor. This is particularly pronounced when F. sporotrichioides CF is added. However, this effect was not observed when F. oxysporum CF was applied. This may be due to the differences in the composition of the mycotoxin complex of this mushroom species from the others used in the study. For further work on the technology of creating oat forms with resistance to mycotoxins of the Fusarium genus fungi, it is assumed to use a level of selective pressure not lower than 40%.

Comprehensive insights into the mechanism of keratin degradation and exploitation of keratinase to enhance the bioaccessibility of soybean protein

Keratin is a recalcitrant protein and can be decomposed in nature. However, the mechanism of keratin degradation is still not well understood. In this study, Bacillus sp. 8A6 can completely degrade the feather in 20 h, which is an efficient keratin degrader reported so far. Comprehensive transcriptome analysis continuously tracks the metabolism of Bacillus sp. 8A6 throughout its growth in feather medium. It reveals for the first time how the strain can acquire nutrients and energy in an oligotrophic feather medium for proliferation in the early stage. Then, the degradation of the outer lipid layer of feather can expose the internal keratin structure for disulfide bonds reduction by sulfite from the newly identified sulfite metabolic pathway, disulfide reductases and iron uptake. The resulting weakened keratin has been further proposedly de-assembled by the S9 protease and hydrolyzed by synergistic effects of the endo, exo and oligo-proteases from S1, S8, M3, M14, M20, M24, M42, M84 and T3 families. Finally, bioaccessible peptides and amino acids are generated and transported for strain growth. The keratinase has been applied for soybean hydrolysis, which generates 2234 peptides and 559.93 mg/L17 amino acids. Therefore, the keratinases, inducing from the poultry waste, have great potential to be further applied for producing bioaccessible peptides and amino acids for feed industry.