determination

摘要： The molecular mechanisms underpinning temperature-dependent sex determination(TSD)in reptiles have attracted great biological interest for many years.However,which genetic factors are essential for TSD remain elusive,especially regarding female sex determination.Cytochrome P450 family 19 subfamily A member 1(Cyp19a1)encodes the endoplasmic reticulum enzyme aromatase,which participates in the catalytic conversion of androgens to estrogens,and is implicated in sexual differentiation in many species.However,whether Cyp19a1 plays a critical role in determining gonadal sexual fate in TSD species remains to be elucidated.In the current study,Cyp19a1 exhibited a temperature-dependent and sexually dimorphic expression pattern,preceding gonadal sex differentiation in a TSD turtle species(Mauremys reevesii).Sexual phenotype of the turtles was successfully reversed by aromatase inhibitor treatment at the female-producing temperature(FPT).Furthermore,exogenous estradiol(E2)treatment led to complete male-to-female sex reversal at the male-producing temperature(MPT),accompanied by rapid up-regulation of Cyp19a1.Thus,Cyp19a1 appears to be essential for female sex determination in M.reevesii,suggesting a vital role in the female TSD pathway.

摘要： Non-allelic recombination between homologous repetitive elements contributes to evolution and human genetic disorders.Here,we combine short-and long-DNA read sequencing of repeat elements with a new bioinformatics pipeline to show that somatic recombination of Alu and L1 elements is widespread in the human genome.Our analysis uncovers tissue-specific non-allelic homologous recombination hallmarks;moreover,we find that centromeres and cancer-associated genes are enriched for retroelements that may act as recombination hotspots.We compare recombination profiles in human-induced pluripotent stem cells and differentiated neurons and find that the neuron-specific recombination of repeat elements accompanies chromatin changes during cell-fate determination.

摘要： In this study,zirconia containing refractory samples were decomposed by dilute nitric acid.The chloride ion content in the leaching solution was determined by thiocyanate spectrophotometry.The influences of the leaching method of the sample pretreatment and the coloration condition of the solution to be tested on the test results were studied.The precision test was carried out and the results were compared with those determined by ion chromatography.The results showed that the zirconia containing refractories were boiled with dilute nitric acid to obtain the test solution.The influence of zirconium hydrolysis on determination was removed by centrifugation.The chlorine contents in zirconia containing refractories determined by spectrophotometry have low relative standard deviation(RSD),showing slight testing difference with those determined by ion chromatograghy.

摘要： A low cost,rapid and sensitive preparation method of silica gel supported ionic liquid(SGSIL)combined with matrix solid phase dispersion(MSPD)followed by high performance liquid chromatography(HPLC)with ultraviolet detection(UV)is proposed,and it was applied to determine the seven active compounds in Salvia Miltiorrhiza herb.SGSIL and ionic liquid[BMIM]BF4 were used as the adsorbent and the green elution reagent in the MSPD procedure.Several extraction conditions including type of filler and elution solvent,the volume of elution solvent,material liquid ratio were optimized.Under the optimum conditions,the SGSIL-MSPD-HPLC method showed a low limit of detection(LOD,S/N=3)of 0.0122-0.8788μg/mL for standard solution,limit of quantification(LOQ,S/N=10)of 0.0406-2.9292μg/mL for standard solution,wide linear range from 1.56 to 2000μg/mL for all compounds for standard solution,correlation coefficients(r)of more than 0.9990,acceptable reproducibility(relative standard deviations,RSDs<3.54%),and precision of RSDs<3.36%for intra-day,RSDs<3.50%for inter-day.The satisfactory recoveries ranged from 96.4 to 102.5,with RSDs less than 3.45%.The developed SGSIL-MSPD method is easier and more suitable for the determination of the seven active compounds in Salvia Miltiorrhiza herb than the traditional ultrasonic extraction.It was an effective and efficient method for the extraction and quantification of the seven active compounds in traditional Chinese herbal samples.

摘要： SOX9(SRY-related HMG box gene 9)is an essential regulator of male sex determination and testis differentiation in many vertebrate species.However,the functional role of Sox9 in testis differentiation has not yet been identified in any reptilian species.Herein,Sox9 knockdown in the red-eared slider turtle(Trachemys scripta)embryos at a male-producing temperature led to complete male-to-female sex reversal,characterized by the formation of an ovary-like structure,disappearance of male marker AMH,and ectopic expression of ovarian regulator FOXL2,as well as a female distribution pattern of germ cells.Conversely,in-ovo overexpression of Sox9 at a female-producing temperature resulted in partial masculinization of putative female embryos,with the coexistence of AMH and FOXL2.Our study provides the first direct evidence that Sox9 is indispensable for testicular differentiation in a reptilian species,further confirming the conserved role of Sox9 in vertebrate sexual development.

摘要： The mixed-ligand complexes of molybdenum(VI) with dithiolphenols (DP) {2,6-dithiol-4-methylphenol (DTMP), 2,6-dithiol-4-ethylphenol (DTEP) and 2,6-dithiol-4-tert-butylphenol (DTBP)} in the presence of hydrophobic amines have been investigated by spectrophotometric method. The condition of complexing and extraction, physical-chemical and analytical characteristics of this complex have been found. As hydrophobic amine 2(N, N-dimethylaminomethyl)-4-methylrphenol (АP1) and 2(N, N-dimethylaminomethyl)-4-xlor-phenol (AP2), 2 (N, N-dimethylamino-methyl)-4-brom-phenol (AP3) were used. It has been found that mixed-ligand complex was formed in weakly acidic medium (pH 4.1 - 5.9). The maximum analytical signal when complexing Mo(V) is observed at 516 - 534 nm. The calculated molar absorption (εmax) belongs to the range (4.16 - 5.35) × 104. The Beer’s law was applicable in the range of 0.3 - 22 μg/ml. The extraction photometric methods of the molybdenum determination were processed. The influence of diverse ions on determination of molybdenum has been studied. The proposed method was applied successfully to determine amount of molybdenum in steel and in soil.

摘要： Tea is grown in Bangladesh under marginal climatic and soil conditions. Its production is greatly influenced by many physical, chemical, biological and natural factors. The increasing land use intensity without adequate and balanced use of chemical fertilizers and with little or no use of organic manure has caused severe fertility deterioration of our soils resulting in stagnating or even declining of crop productivity. The need of the hour is to achieve substantially higher crop yield than the present yield levels from our limited land resources on a sustainable basis. A feasibility study was carried out of one and only organic tea garden namely Kazi & Kazi Tea Estate at Panchaghar and compared to ordinary tea gardens located at Sylhet namely Zareen Tea Estate, Nurjahan Tea Estate and Malnichara Tea Estate as secondary data to investigate the fertility status of soil. Results of the present study showed that soil solutions were acidic in nature in all seasons. Medium to high soil organic matter, medium to high available iron and phosphorous, and low availability of potash showed that soils were not sufficiently fertile for crop production. Student t-test values of all the parameters with control sample showed statistically significant results for SOM and available P. The critical values have been fixed at 0.1% for N and 1% for OM, 10 μg/g for P, 80 μg/g for K, 25 μg/g for Mg, 90 μg/g for Ca, 2 μg/g for Zn and 20 μg/g for S. The nutrient status is much higher in Kazi & Kazi organic tea estate in compared to other ordinary tea estates in Bangladesh.

摘要： Mesenchymal stem cells(MSCs)are adult stem cells harboring self-renewal and multilineage differentiation potential that are capable of differentiating into osteoblasts,adipocytes,or chondrocytes in vitro,and regulating the bone marrow microenvironment and adipose tissue remodeling in vivo.The process of fate determination is initiated by signaling molecules that drive MSCs into a specific lineage.Impairment of MSC fate determination leads to different bone and adipose tissue-related diseases,including aging,osteoporosis,and insulin resistance.Much progress has been made in recent years in discovering small molecules and their underlying mechanisms control the cell fate of MSCs both in vitro and in vivo.In this review,we summarize recent findings in applying small molecules to the trilineage commitment of MSCs,for instance,genistein,medicarpin,and icariin for the osteogenic cell fate commitment;isorhamnetin,risedronate,and arctigenin for pro-adipogenesis;and atractylenolides and dihydroartemisinin for chondrogenic fate determination.We highlight the underlying mechanisms,including direct regulation,epigenetic modification,and post-translational modification of signaling molecules in the AMPK,MAPK,Notch,PI3K/AKT,Hedgehog signaling pathways etc.and discuss the small molecules that are currently being studied in clinical trials.The target-based manipulation of lineage-specific commitment by small molecules offers substantial insights into bone marrow microenvironment regulation,adipose tissue homeostasis,and therapeutic strategies for MSC-related diseases.

摘要： A very simple, ultra-sensitive, highly selective and non-extractive new spectrofluorimetric method for the determination of arsenic at pico-trace levels using 2-(α-pyridyl)-thioquinaldinamide (PTQA) has been developed. PTQA has been proposed as a new analytical reagent for the direct non-extractive spectrofluorimetric determination of Arsenic (V). This novel fluorimetric reagent, PTQA becomes oxidized in a slightly acidic (0.025 - 0.1 M H2SO4) solution with Arsenic (V) in absolute ethanol to produce highly fluorescent oxidized product (λex = 303 nm;λem = 365 nm). Constant and maximum fluorescence intensities were observed over a wide range of acidity (0.025 - 0.1 M H2SO4) for the period between 2 min and 24 h. Linear calibration graphs were obtained for 0.001 - 800-μgL-1 of As, having a detection limit of 0.1-ngL-1;the quantification limit of the reaction system was found to be 1-ngL-1 and the RSD was 0% - 2%. A large excess of over 60 cations, anions and complexion agents (like, chloride, phosphate, azide, tartrate, oxalate, SCN, etc.) do not interfere in the determination. The developed method was successfully used in the determination of arsenic in several Certified Reference Materials (alloys, steels, ores, human urine, hair, nails, bovine liver and sediments) as well as in some biological fluids (human blood, urine, hair, nail and milk), soil samples, food samples (vegetables, fruits, rice, corn and wheat), solutions containing both arsenic (III) and arsenic (V) speciation and complex synthetic mixtures. The results of the proposed method for assessing biological, food and soil samples were comparable with both ICP-OES & AHG-AAS and were found to be in excellent agreement.