A New Micropropagation Technology of Tilia amurensis:In VitroMicropropagation of Mature Zygotic Embryos and the Establishment of a PlantRegeneration System

Tilia amurensis is an economically valuable broadleaf tree species in Northeast China.The production of highqualityT.amurensis varieties at commercial scales has been greatly limited by the low germination rates.Thereis thus a pressing need to develop an organogenesis protocol for in vitro propagation of T.amurensis to alleviate ashortage of high-quality T.amurensis seedlings.Here,we established a rapid in vitro propagation system forT.amurensis from mature zygotic embryos and analyzed the effects of plant growth regulators and culture mediain different stages.We found that Woody plant medium(WPM)was the optimal primary culture medium formature zygotic embryos.The highest callus induction percentage(68.76%)and number of axillary buds induced(3.2)were obtained in WPM+0.89μmol/L 6-benzyladenine(6-BA)+0.46μmol/L kinetin(KT)+0.25μmol/Lindole-3-butryic acid(IBA)+1.44μmol/L gibberellin A_(3)(GA_(3)).The multiple shoot bud development achievedthe highest percentage(83.32%)in the Murashige and Skoog(MS)+2.22μmol/L 6-BA+0.25μmol/L IBA+1.44μmol/L GA_(3).The rooting percentage(96.70%)was highest in 1/2 MS medium+1.48μmol/L IBA.Thesurvival percentage of transplanting plantlets was 82.22%in soil:vermiculite:perlite(5:3:1).Our study is the firstto establish an effective organogenesis protocol for T.amurensis using mature zygotic embryos.

Endogenous biosynthesis of docosahexaenoic acid(DHA)regulates fish oocyte maturation by promoting pregnenolone production

Omega-3 polyunsaturated fatty acids(n-3 PUFAs),particularly docosahexaenoic acid(22:6n-3,DHA),play crucial roles in the reproductive health of vertebrates,including humans.Nevertheless,the underlying mechanism related to this phenomenon remains largely unknown.In this study,we employed two zebrafish genetic models,i.e.,elovl2^(-/-)mutant as an endogenous DHAdeficient model and fat1(omega-3 desaturase encoding gene)transgenic zebrafish as an endogenous DHA-rich model,to investigate the effects of DHA on oocyte maturation and quality.Results show that the elovl2^(-/-)mutants had much lower fecundity and poorer oocyte quality than the wild-type controls,while the fat1 zebrafish had higher fecundity and better oocyte quality than wildtype controls.DHA deficiency in elovl2^(-/-)embryos led to defects in egg activation,poor microtubule stability,and reduced pregnenolone levels.Further study revealed that DHA promoted pregnenolone synthesis by enhancing transcription of cyp11a1,which encodes the cholesterol side-chain cleavage enzyme,thereby stabilizing microtubule assembly during oogenesis.In turn,the hypothalamic-pituitary-gonadal axis was enhanced by DHA.In conclusion,using two unique genetic models,our findings demonstrate that endogenously synthesized DHA promotes oocyte maturation and quality by promoting pregnenolone production via transcriptional regulation of cyp11a1.

Production of marker-free transgenic plants from mature tissues of navel orange using a Cre/loxP site-recombination system

Genetic transformation with mature material as the explants could shorten the transgenic period and avoid seed dependence compared with genetic transformation using the epicotyl seedling stem segments as the receptor. Here, we constructed an Agrobacterium tumefaciensmediated transformation for generation of marker-free transgenic plants from navel orange(Citrus sinensis Osbeck) mature stems using a CreloxP recombination system. To efficiently recover the regenerated buds from mature tissues, five recovery methods were compared: in vitro micrografting of 0.1-0.5(1-2 weeks), > 0.5 cm(3-4 weeks) and > 1 cm long lignified bud and in vitro micrografting of explants with a bud and rooting regenerated bud. The data showed that in vitro micrografting of > 1 cm long regenerated bud with expanded leaves after one month of continuous culture for lignification was the optimal solution for plant recovery from mature tissues. Transgenic plants without selectable marker genes were created from navel orange(Citrus sinensis Osbeck) tissue using a transformation vector PLI-35SPR1aCB containing a Cre/loxP system recombination together with genes encoding the selectable marker isopentenyl transferase(IPT) and an anti-bacterial peptide(PR1aCB).Using IPT positive selection, the transformation efficiency determined by PCR was 0.9%, and in total, 20 transgenic plants were obtained.Southern blotting confirmed further their transgenicity. PCR and sequencing analysis demonstrated that both the Cre and IPT genes had been successfully removed from the transgenic plants(deletion efficiency 100%). Over all, using Cre/loxP system recombination together with the IPT positive selection, marker-free transgenic plants can be recovered efficiently from mature tissues of navel orange(Citrus sinensis Osbeck), which provides a potential method for production of transgenic plants from citrus mature tissue.

Impact of stage-specific limb function exercises guided by a selfmanagement education model on arteriovenous fistula maturation status

BACKGROUND The exercise of limb function is the most economical and safe method to promote the maturation of arteriovenous fistula(AVF).However,due to the lack of a uni-fied exercise standard in China,many patients have insufficient awareness of the importance of AVF,leading to poor effectiveness of limb function exercise.The self-management education model can effectively promote patients to take pro-active health-related actions.This study focuses on the characteristics of patients during the peri-AVF period and conducts a phased limb function exercise under the guidance of the self-management education model to observe changes in fac-tors such as the maturity of AVF.AIM To assess the impact of stage-specific limb function exercises,directed by a self-management education model,on the maturation status of AVFs.METHODS This study is a randomized controlled trial involving 74 patients with forearm AVFs from the Nephrology Department of a tertiary hospital in Sichuan Province,China.Patients were randomly divided into an observation group and a control group using a random number table method.The observation group underwent tailored stage-specific limb func-tion exercises,informed by a self-management education model which took into account the unique features of AVF at various stages,in conjunction with routine care.Conversely,the control group was given standard limb function exercises along with routine care.The assessment involves the maturity of AVFs post-intervention,post-operative complications,and the self-management level of the fistula in both groups patients.Analyses were conducted using SPSS version 23.0.Count data were represented by frequency and percentage and subjected to chi-square test comparisons.Measurement data adhering to a normal distribution were presented as mean±SD.The independent samples t-test was utilized for inter-group comparisons,while the paired t-test was used for intra-group comparisons.For measurement data not fitting a normal distribution,the median and interquartile range were presented and analyzed using the Wilcoxon rank sum test.RESULTS At the 8-wk postoperative mark,the observation group demonstrated significantly higher scores in AVF symptom recognition,symptom prevention,and self-management compared to the control group(P<0.05).However,the variance in symptom management scores between the observation and control groups lacked statistical signi-ficance(P>0.05).At 4 wk after the operation,the observation group displayed a superior vessel diameter and depth from the skin of the drainage vessels in comparison to the control group(P<0.05).While the observation group did manifest elevated blood flow rates in the drainage vessels relative to the control group,this distinction was not statistically significant(P>0.05).By the 8-wk postoperative interval,the observation group outperformed the control group with notable enhancements in blood flow rates,vessel diameter,and depth from the skin of drainage vessels(P<0.01).Seven days following the procedure,the observation group manifested significantly diminished limb swelling and an overall reduced complication rate in contrast to the control group(P<0.05).The evaluation of infection,thrombosis,embolism,arterial aneurysm stenosis,and incision bleeding showed no notable differences between the two groups(P>0.05).By the 4-wk postoperative juncture,complications between the observation and control groups were statistically indistinguishable(P>0.05).CONCLUSION Stage-specific limb function exercises,under the guidance of a self-management education model,amplify the capacity of AVF patients to discern and prevent symptoms.Additionally,they expedite AVF maturation and miti-gate postoperative limb edema,underscoring their efficacy as a valuable method for the care and upkeep of AVF in hemodialysis patients.

Lamellar Bodies Count (LBC) as a Predictor of Fetal Lung Maturity in Preterm Premature Rupture of Membranes Compared to Neonatal Assessment

Background: Respiratory distress syndrome (RDS) is a major cause of neonatal morbidity and mortality, affecting approximately 1% of all live births and 10% of all preterm infants. Lamellar bodies represent a storage form of pulmonary surfactant within Type II pneumocytes, secretion of which increases with advancing gestational age, thus enabling prediction of the degree of FLM. Preterm premature rupture of membranes (PPROM) complicates approximately 1/3 of all preterm births. Birth within 1 week is the most likely outcome for any patient with PPROM in the absence of adjunctive treatments. Respiratory distress has been reported to be the most common complication of preterm birth. Sepsis, intraventricular haemorrhage, and necrotizing enterocolitis also are associated with prematurity, but these are less common near to term. Objective: To assess the efficacy of the amniotic fluid lamellar body counting from a vaginal pool in predicting fetal lung maturity in women with preterm premature rupture of membranes. Methods: This study was conducted at Ain Shams University Maternity Hospital in the emergency ward from January 2019 to September 2019. It included 106 women with singleton pregnancies, gestational age from 28 - 36 weeks with preterm premature rupture of membranes. This study is designed to assess the efficacy of the amniotic fluid lamellar body counting (LBC) from a vaginal pool in predicting fetal lung maturity in women with preterm premature rupture of membranes. Results: The current study revealed a highly significant increase in the lamellar body count in cases giving birth to neonates without RDS compared to that cases giving birth to neonates with RDS. Also, no statistically significant difference between LBC and age, parity and number of previous miscarriages in the mother was found. Gestational age at delivery was significantly lower among cases with respiratory distress. Steroid administration was significantly less frequent among cases with respiratory distress. However, lamellar bodies had high diagnostic performance in the prediction of respiratory distress. Conclusion: Lamellar body count (LBC) is an effective, safe, easy, and cost-effective method to assess fetal lung maturity (FLM). It does not need a highly equipped laboratory or specially trained personnel, it just needs the conventional blood count analyzer. Measurement of LBC is now replacing the conventional Lecithin/Sphyngomyelin L/S ratio. LBC cut-off value of ≤42.5 × 103/μL can be used safely to decide fetal lung maturity with sensitivity of 95.7% and specificity of 97.6%.

Estimation of Peanut Maturity Using Color Image Analysis

Peanuts pods grow underground and mature unevenly, resulting that choosing the correct time to harvest is more complicated than other crops. Pod maturity can be determined by blasting with a pressure washer to remove outer skin of the pod (exocarp) to expose the color of the middle layer (mesocarp). The mesocarp color changes with maturity from white to yellow, orange, brown and finally black. The sum of percentage from orange, brown, and black mesocarp (OBB) color and black color (BL) represents the kernels that are mature enough to harvest. The goal of this research is to identify methodologies to estimate OBB and BL of the pods using RGB images taken in the field and validate the proposed model using other pod images. The Mahalanobis distance classification method was used to process sets of images and calculate pod area (number of pixels) corresponding to two classes (mesocarp and background) with nine different color groups. The results showed a performance of 94% effectiveness for mesocarp using Mahalanobis distance classification. Statistical regression for OBB and BL was developed based on 315 images of peanut pods taken from the field. The R2 and root mean square error of predicted and actual OBB were 0.93 and 4.1%, respectively. The R2 and root mean square error of predicted and actual BL were 0.88 and 1.8%, respectively. The validation of OBB using other images provided reasonable estimation (R2 = 0.98 and RMSE = 2.73%). This study introduces a novel, cost-effective, and non-destructive method for estimating peanut maturity using RGB imagery and Mahalanobis distance classification in the field. This innovative approach addresses the limitations of traditional methods and offers a robust alternative for real-time maturity assessment.

Studies of the Variability of Primary Metabolites in the Epicarp, Mesocarp and Seed of Dacryodes edulis Fruit at Taste Maturity

The fruits of Dacryodes edulis are rich in biologically active substances, which makes them of great interest in terms of validation. In this study, we targeted the primary metabolites in the epicarp, the mesocarp and the seed of the fruit of Dacryodes edulis at taste maturity, which were selected for their nutritional quality and its appreciation throughout the Gulf of Guinea area, which is very popular because of its large size, texture and special taste. The evaluation of total carbohydrates, total lipids and soluble proteins in the epicarp, mesocarp and seed of the fruit at taste maturity was made from spectrophotometer measurements. The overall analysis of the results of the present study shows that total carbohydrates, total lipids and proteins accumulate more in the seed with respectively 251.33 ± 1.15 mg/g DM;9.92 ± 0.201 mg/g DM and 55.075 ± 0.024 mg/g DM. Likewise, the results indicate low concentrations of total carbohydrates and total lipids in the epicarp with respectively 245 ± 1 mg/g DM and 4.77 ± 0.047 mg/g DM, on the other hand, it is the mesocarp which presents the lowest content of soluble proteins: 28.075 ± 3.231 mg/g DM. This variation could be linked to the nature of the compartment, more particularly to the storage location. This comparative study could lead to the valorization of the seed of the fruit of Dacryodes edulis for its richness in metabolites and arouse significant interest in nutrition.

Neurovascular unit on a chip:the relevance and maturity as an advanced in vitro model

The brain is a high-energy demanding organ,consuming around 20%of the metabolic energy generated.To fulfill this demand,cerebral blood flow(CBF)supplies oxygen and glucose continuously through the intricate network of cerebral blood vessels.Although for many years brain activity and blood flow were conceived as independent processes,MRI-based functional brain imaging demonstrated that there is a coupling between them.

Enhancer of Shoot Regeneration 2(ESR2)regulates pollen maturation and vitality in watermelon(Citrullus lanatus)

Watermelon(Citrullus lanatus)holds global significance as a fruit with high economic and nutritional value.Exploring the regulatory network of watermelon male reproductive development is crucial for developing male sterile materials and facilitating cross-breeding.Despite its importance,there is a lack of research on the regulation mechanism of male reproductive development in watermelon.In this study,we identified that ClESR2,a VIIIb subclass member in the APETALA2/Ethylene Responsive Factor(AP2/ERF)superfamily,was a key factor in pollen development.RNA insitu hybridization confirmed significantClESR2 expression in the tapetum and pollen during the later stage of anther development.The pollens of transgenic plants showed major defects in morphology and vitality at the late development stage.The RNA-seq and protein interaction assay confirmed that ClESR2 regulates pollen morphology and fertility by interacting with key genes involved in pollen development at both transcriptional and protein levels.These suggest that Enhancer of Shoot Regeneration 2(ESR2)plays an important role in pollen maturation and vitality.This study helps understand the male reproductive development of watermelon,providing a theoretical foundation for developing male sterile materials.

A Proposed Approach for Measuring Maturity Level of Software Delivery

Software delivery is vital for modern organizations, driving innovation and competitiveness. Measuring an organization’s maturity in software delivery is crucial for efficiency and quality. The Capability Maturity Model (CMM) framework provides a roadmap for improvement but assessing an organization’s CMM Level is challenging. This paper offers a quantitative approach tailored to the CMM framework, using Goal-Question-Metric (GQM) frame-works for each key process area (KPA). These frameworks include metrics and questions to compute maturity scores effectively. The study also refines practices into questions for a thorough assessment. The result is an Analysis Matrix that calculates weighted scores and an overall maturity score. This approach helps organizations assess and enhance their software delivery processes systematically, aiming for improved practices and growth.

Effect of thermal maturation and organic matter content on oil shale fracturing

The Pabdeh Formation represents organic matter enrichment in some oil fields,which can be considered a source rock.This study is based on the Rock–Eval,Iatroscan,and electron microscopy imaging results before and after heating the samples.We discovered this immature shale that undergoes burial and diagenesis,in which organic matter is converted into hydro-carbons.Primary migration is the process that transports hydrocarbons in the source rock.We investigated this phenomenon by developing a model that simulates hydrocarbon generation and fluid pressure during kerogen-to-hydrocarbon conversion.Microfractures initially formed at the tip/edge of kerogen and were filled with hydrocarbons,but as catagenesis progressed,the pressure caused by the volume increase of kerogen decreased due to hydrocarbon release.The transformation of solid kerogen into low-density bitumen/oil increased the pressure,leading to the development of damage zones in the source rock.The Pabdeh Formation’s small porethroats hindered effective expulsion,causing an increase in pore fluid pressure inside the initial microfractures.The stress accumulated due to hydrocarbon production,reaching the rock’s fracture strength,further contributed to damage zone development.During the expansion process,microfractures preferentially grew in low-strength pathways such as lithology changes,laminae boundaries,and pre-existing microfractures.When the porous pressure created by each kerogen overlapped,individual microfractures interconnected,forming a network of microfractures within the source rock.This research sheds light on the complex interplay between temperature,hydrocarbon generation,and the development of expulsion fractures in the Pabdeh Formation,providing valuable insights for understanding and optimizing hydrocarbon extraction in similar geological settings.

Characterization of early maturing elite genotypes based on MTSI and MGIDI indexes:an illustration in upland cotton(Gossypium hirsutum L.)

Background Globally,the cultivation of cotton is constrained by its tendency for extended periods of growth.Early maturity plays a potential role in rainfed-based multiple cropping system especially in the current era of climate change.In the current study,a set of 20 diverse Gossypium hirsutum genotypes were evaluated in two crop seasons with three planting densities and assessed for 11 morphological traits related to early maturity.The study aimed to identify genotype(s)that mature rapidly and accomplish well under diverse environmental conditions based on the two robust multivariate techniques called multi-trait stability index(MTSI)and multi-trait genotype-ideotype distance index(MGIDI).Results MTSI analysis revealed that out of the 20 genotypes,three genotypes,viz.,NNDC-30,A-2,and S-32 accomplished well in terms of early maturity traits in two seasons.Furthermore,three genotypes were selected using MGIDI method for each planting densities with a selection intensity of 15%.The strengths and weaknesses of the genotypes selected based on MGIDI method highlighted that the breeders could focus on developing early-maturing genotypes with specific traits such as days to first flower and boll opening.The selected genotypes exhibited positive genetic gains for traits related to earliness and a successful harvest during the first and second pickings.However,there were negative gains for traits related to flowering and boll opening.Conclusion The study identified three genotypes exhibiting early maturity and accomplished well under different planting densities.The multivariate methods(MTSI and MGIDI)serve as novel approaches for selecting desired genotypes in plant breeding programs,especially across various growing environments.These methods offer exclusive benefits and can easily construe and minimize multicollinearity issues.

CRISPR/Cas9-mediated knockout of E4 gene promotes maturation in soybean

Soybean is a broadly popular and extensively cultivated crop,however,many high-yield and high-quality varieties require specific growth conditions,restricting their widespread adoption.The appropriate light conditions and photoperiod must be attained for these varieties to thrive in new environments.In this study,we employed CRISPR/Cas9 to design two sgRNAs aimed at knocking out the maturity-related gene E4 in a major American soybean variety called''Jack'',which belongs to maturity group MGII.E4 gene is primarily involved in the photoperiodic flowering and maturity in soybean,making it an ideal candidate for genetic manipulation.We successfully obtained 1 homozygous E4-SG1 mutant type with 1-bp insertion,and 4 homozygous E4-SG2 mutants type with 2-bp deletion,7-bp deletion,61-bp deletion,and 1-bp insertion,respectively.The homozygous e4 mutant plants contained early termination codons devoid of transgenic elements.Additionally,no potential offtarget sites of the E4 gene were detected.A comparative analysis revealed that,unlike the wild-type,the maturity time of homozygous e4 mutants was early under both short-day and long-day conditions.These mutants offer novel germplasm resources that may be used to modify the photoperiod sensitivity and maturity of soybean,enhancing its adaptability to high-latitude regions.

Correlation analysis of interstitial maturity and prognosis of colorectal cancer:Meta-analysis

BACKGROUND To investigate the relationship between interstitial maturity and prognosis of colorectal cancer.AIM To examine the correlation between interstitial maturity and the prognosis of colorectal cancer.METHODS The paper database PubMed,EMBASE,Cochranelibrary,Springerlink,CNKI,and Wanfang database were searched until December 2023."tumor stroma maturity""desmoplastic stroma reaction""desmoplastic reaction""stroma reaction""degree of stroma reaction""stroma classification""stroma density""colorectal cancer""colon cancer""rectal cancer""prognosis"were searched for the search terms.Two system assessors independently screened the literature quality according to the inclusion exclusion criteria,Quality evaluation and data extraction were performed for the included literatures,and meta-analysis was performed for randomized control trials included at using Review Manager 5.2 software.RESULTS Finally,data of 9849 patients with colorectal cancer from 19 cosets in 15 literatures were included,including 4339 patients with mature type(control group),3048 patients with intermediate type(intermediate group)and 2456 patients with immature type(immature group).The results of meta-analysis showed:Relapse-free survival[hazard ratio(HR)=2.66,95%confidence interval(CI):2.30-3.08;P<0.00001],disease-free survival(HR=3.68,95%CI:2.33-5.81;P<0.00001)and overall survival(HR=1.70,95%CI:1.53-1.87;P<0.00001)were significantly lower than those in mature group(control group);relapse-free survival(HR=1.36,95%CI:1.17-1.59;P<0.0001)and disease-free survival rate(HR=1.85,95%CI:1.53-2.24;P<0.0001)was significantly lower than the mature group(control group).CONCLUSION There is the correlation between tumor interstitial maturity and survival prognosis of colorectal cancer,and different degrees of tumor interstitial maturity have a certain impact on the quality of life of colorectal cancer patients.

Debugging Strategies for Parents' Educational Anxiety in the Transition from Kindergarten to Primary School--Based on the Theory of Mature Forces

Due to the rapid growth of the economy and society,the burden of social security has been increasingly escalating,resulting in a continuous rise in parenting stress among certain groups of parents.On one hand,these parents aspire for their young children to grow through play;on the other hand,they are acutely aware that early childhood education constitutes the foundational stage of basic education and serves as the commencement phase of lifelong learning.Thus,they recognize the importance of emphasizing early childhood education.Therefore,preschool education has been given important significance.Parents place particular emphasis on education during this stage.They actively leverage their educational,financial,and social advantages to create favorable educational resources and opportunities for their young children.However,to a certain extent,this exacerbates educational anxiety among a segment of parents.Despite the implementation of various governmental measures,it appears that these initiatives have not fundamentally addressed parental educational anxiety at its root.This study employs interview techniques and literature review methodologies to gain a profound understanding of parental educational anxiety during the transition from early childhood to primary education.By integrating Gesell's Maturation Theory,this research aims to scientifically explicate the developmental patterns of children.Consequently,it endeavors to enable non-professional parents to adopt a"professional"perspective in their approach towards early childhood education.

“Component flow”conditions and its effects on enhancing production of continental medium-to-high maturity shale oil

Based on the production curves,changes in hydrocarbon composition and quantities over time,and production systems from key trial production wells in lacustrine shale oil areas in China,fine fraction cutting experiments and molecular dynamics numerical simulations were conducted to investigate the effects of changes in shale oil composition on macroscopic fluidity.The concept of“component flow”for shale oil was proposed,and the formation mechanism and conditions of component flow were discussed.The research reveals findings in four aspects.First,a miscible state of light,medium and heavy hydrocarbons form within micropores/nanopores of underground shale according to similarity and intermiscibility principles,which make components with poor fluidity suspended as molecular aggregates in light and medium hydrocarbon solvents,such as heavy hydrocarbons,thereby decreasing shale oil viscosity and enhancing fluidity and outflows.Second,small-molecule aromatic hydrocarbons act as carriers for component flow,and the higher the content of gaseous and light hydrocarbons,the more conducive it is to inhibit the formation of larger aggregates of heavy components such as resin and asphalt,thus increasing their plastic deformation ability and bringing about better component flow efficiency.Third,higher formation temperatures reduce the viscosity of heavy hydrocarbon components,such as wax,thereby improving their fluidity.Fourth,preservation conditions,formation energy,and production system play important roles in controlling the content of light hydrocarbon components,outflow rate,and forming stable“component flow”,which are crucial factors for the optimal compatibility and maximum flow rate of multi-component hydrocarbons in shale oil.The component flow of underground shale oil is significant for improving single-well production and the cumulative ultimate recovery of shale oil.

Callus Induction from Mature Embryos of Maize

In this study we studied the factors influencing the callus induction from mature embryos of maize inbred lines Qi 319, Zhen 58, Chang 7 -2, Lx 9801 and 81162, such as genotype, combination of plant growth regulators, and low-temperature pretreatment. The results showed that the induction rate of Qi 319 was the highest among the four genotypes tested; combination of 4.0 mg/L 2,4-D ＋ 0.5 mg/L 6-BA was suitable for inducing callus from mature embryos; three days of 4℃ pretreatment can promote the callus induction significantly. The indices optimized in the present study are helpful for establishing genetic transformation system in maize without considering seasonal variation.

Callus Induction and Plant Regeneration from Mature Seeds of Perennial Ryegrass

Objective The aim was to explore callus induction and plant regeneration of perennial ryegrass, as well as provide the foundation for transgenic research on perennial ryegrass.[ Methed] Mature seeds of perennial ryegrass were used as explants to study the effects of different hormone compositions on callus induction, proliferation and plant differentiation. Result The result showed that the induction rate achieved its highest on 2,4-D of 8 mg/L combining with 6-BA of 0.025 mg/L, which was up to 56.42%. Callus were differentiated after two to three generations, the highest differentiation rate 34.14% was achieved in the medium contained MS medium with 6-BA of 2 mg/L, and the differentiation rate was obviously affected by the callus condition after proliferation. The root inducing medium, containing 0.5 mg/L NAA and MS medium with half of macroelement, gained 98% root inducing rate. Conclusien A high frequency genetic regeneration system was established.

Effects of Genotypes and Basic Medium on Culture of Maize Mature Embryos

[Objective]This study was to screen out suitable genotypes and basic medium for the culture of maize mature embryos.[Method]Using mature embryos of nine maize genotypes as explants,the effects of genotypes and basic medium on callus induction and subculture were investigated.[Result]The genotypes performed better in callus induction and subculture were found in turn 853-35,853-209,Dan 34 and 81162.MS medium is better than N6 medium in the callus induction from maize embryos,while N6 medium is more suitable for callus subculture.[Conclusion]Our study further improved the tissue culture system in maize with mature embryos as explants.

Optimizing Yanbian Cow Oocytes Mature in vitro and Cleavage System after Nuclear Transfer Based on Uniform Design

[Objective] The aim was to optimize Yanbian cow oocytes mature in vitro and cleavage system after nuclear transfer based on uniform design. [Method] Oocytes were recovered by aspiration method, and oocytes were matured in vitro （IVM） with different conditions, and then carried out nucleus transfer, fusion, activation and in vitro culture （IVC） of embryo. Effects of ovary storage temperature, maturation time and follicular diameter size on in vitro maturation and cleavage rates of cow oocytes were compared. [ Result] The best conditions of IVM of Yanbian cow oocytes was that： the oocytes of 8 mm diameter were matured in vitro for 24 hours when the ovaries were stored at 26℃ or 31 ℃. The best cleave conditions after nucleus transfer of oocytes was that： the oocytes of 6 mm or 8 mm diameter were cultured in vitro for 24 hours when the ovaries were stored at 26℃. [ Conclusion] The result has some reference to Yanbian cow and other cow breeding and population expanding propagation.