Differences between two wheat genotypes in the development of floret primordia and contents of pigments and hormones

Promoting more floret primordia within a spike to acquire fertile potential during the differentiation and pre-dimorphism phases is critical for increasing the number of fertile florets per spike(NFFs).However,it is yet unknown the physiological mechanism regulating the complex and dynamic process.This study aimed to clarify how intra-spike hormones,pigments,and assimilates coordinate with each other to regulate spike morphology and then floret primordia development.A two-year field experiment was conducted with two winter wheat genotypes:N50(big-spike with greater NFFs)and SM22(mediumspike with fewer NFFs).We monitored high temporal and spatial-resolution changes in the number and morphology of floret primordia within a spike,as well as in intra-spike hormones,pigments,and assimilates.Our results revealed that the big-spike genotype had more NFFs than the medium-spike genotype,not only because they had more spikelets,but also because they had greater NFFs mainly at central spikelets.More floret primordia at central spikelets had sufficient time to develop and acquire fertile potential during the differentiation phase(167-176 d after sowing,DAS)and the pre-dimorphism phase(179 DAS)for the big-spike genotype than the medium-spike genotype.Floret primordia with fertile morphology during the pre-dimorphism phase always developed into fertile florets during the dimorphism phase.Those early-developed floret primordia most proximal and intermediate to the rachis in the big-spike genotype developed faster than the medium-spike genotype.Correspondingly,the spike dry matter and pigments(chlorophyll a,chlorophyll b,carotene,and carotenoids)content during 170-182 DAS,auxin(IAA)and cytokinin(CTK)content on 167 DAS were significantly higher in the big-spike genotype than in the medium-spike genotype,while jasmonic acid(JA)content was significantly lower in the big-spike genotype compared to the medium-spike genotype during 167-182 DAS.Since the significant differences in intra-spike hormone content of the two genotypes appear earlier than those in dry matter and pigments,we propose a possible model that helped the N50 genotype(big-spike)to form more fertile florets,taking the intra-spike hormone content as a signaling molecule induced assimilates and pigments synthesis,which accelerated the development of more floret primordia during the differentiation phase and then acquired fertile potential during the pre-dimorphism phase,finally improved the NFFs.Our high temporal and spatial-resolution analysis provides an accurate time window for precision cultivation and effective physiological breeding to improve the number of fertile florets in wheat.

Relationship between tea pigments and health: A bibliometric and visual analysis

Tea pigments have significant effects on human health.However,more attention have been paid to their physiological functions.The aim of this study was to analyze the quantitative and qualitative impact of tea pigments on human health,together with their current and potential future research directions.The study searched and screened 520 publications on WOS from January 2002 to December 2022.The article collected and collated literature published in the last 20 years and analyzed it bibliometrically for years,journals,countries,authors,topics,keywords and strongest citation bursts.The findings of keywords and strongest citation bursts revealed that the most discussed research topics were anticancer,black tea polyphenol,antioxidant,activator inhibitor,in vivo,gut microbiota,and summarize the relevant literature.As a reference for future research,the literature pointed out current shortcomings and speculated future development trend of tea pigments.

Role of foliar spray of plant growth regulators in improving photosynthetic pigments and metabolites in Plantago ovata (Psyllium) under salt stress–A field appraisal

Salinity is one of the major abiotic factors that limit the growth and productivity of plants.Foliar application of plant growth regulators(PGRs)may help plants ameliorate the negative impacts of salinity.Thus,a field experiment was conducted at the Botanical Garden University of Balochistan,Quetta,to explore the potential role of PGRs,i.e.,moringa leaf extract(MLE;10%),proline(PRO;1μM),salicylic acid(SA;250μM),and thiourea(TU;10 mM)in ameliorating the impacts of salinity(120 mM)on Plantago ovata,an important medicinal plant.Salinity hampered plant photosynthetic pigments and metabolites but elevated oxidative parameters.However,foliar application of PGRs enhanced photosynthetic pigments,including Chl b(21.11%),carotenoids(57.87%)except Chl a,activated the defense mechanisms by restoring and enhancing the metabolites,i.e.,soluble sugars(49.68%),soluble phenolics(33.34%),and proline(31.47%),significantly under salinity stress.Furthermore,foliar supplementation of PGRs under salt stress led to a decrease of about 43.02%and 43.27%in hydrogen peroxide and malondialdehyde content,respectively.Thus,PGRs can be recommended for improved photosynthetic efficiency and metabolite content that can help to get better yield under salt stress,with the best and most effective treatments being those of PRO and MLE to predominately ameliorate the harsh impacts of salinity.

An overview of pigment gland morphogenesis and its regulatory mechanism

Cotton has enormous economic potential,providing high-quality protein,oil,and fibre.But the comprehensive utilization of cottonseed is limited by the presence of pigment gland and its inclusion.Pigment gland is a common characteristic of Gossypium genus and its relatives,appearing as visible dark opaque dots in most tissues and organs of cotton plants.Secondary metabolites,such as gossypol,synthesized and stored in the cavities of pigment glands act as natural phytoalexins,but are toxic to humans and other monogastric animals.However,only a few cotton genes have been identified as being associated with pigment gland morphogenesis to date,and the developmental processes and regulatory mechanism involved in pigment gland formation remain largely unclear.Here,the research progress on the process of pigment gland morphogenesis and the genetic basis of cotton pigment glands is reviewed,for providing a theoretical basis for cultivating cotton with the ideal pigment gland trait.

Inhibition of EGFR attenuates EGF-induced activation of retinal pigment epithelium cell via EGFR/AKT signaling pathway

AIM:To explore the effect of epidermal growth factor receptor(EGFR)inhibition by erlotinib and EGFR siRNA on epidermal growth factor(EGF)-induced activation of retinal pigment epithelium(RPE)cells.METHODS:Human RPE cell line(ARPE-19 cells)was activated by 100 ng/mL EGF.Erlotinib and EGFR siRNA were used to intervene EGF treatment.Cellular viability,proliferation,and migration were detected by methyl thiazolyl tetrazolium(MTT)assay,bromodeoxyuridine(BrdU)staining assay and wound healing assay,respectively.EGFR/protein kinase B(AKT)pathway proteins and N-cadherin,α-smooth muscle actin(α-SMA),and vimentin were tested by Western blot assay.EGFR was also determined by immunofluorescence staining.RESULTS:EGF treatment for 24h induced a significant increase of ARPE-19 cells’viability,proliferation and migration,phosphorylation of EGFR/AKT proteins,and decreased total EGFR expression.Erlotinib suppressed ARPE-19 cells’viability,proliferation and migration through down regulating total EGFR and AKT protein expressions.Erlotinib also inhibited EGF-induced an increase of proliferative and migrative ability in ARPE-19 cells and clearly suppressed EGF-induced EGFR/AKT proteins phosphorylation and decreased expression of N-cadherin,α-SMA,and vimentin proteins.Similarly,EGFR inhibition by EGFR siRNA significantly affected EGF-induced an increase of cell proliferation,viability,and migration,phosphorylation of EGFR/AKT proteins,and up-regulation of N-cadherin,α-SMA,and vimentin proteins.CONCLUSION:Erlotinib and EGFR-knockdown suppress EGF-induced cell viability,proliferation,and migration via EGFR/AKT pathway in RPE cells.EGFR inhibition may be a possible therapeutic approach for proliferative vitreoretinopathy(PVR).

Hepatocyte growth factor promotes retinal pigment epithelium cell activity through MET/AKT signaling pathway

AIM:To explore the effects of hepatocyte growth factor(HGF)on retinal pigment epithelium(RPE)cell behaviors.METHODS:The human adult retinal pigment epithelial cell line-19(ARPE-19)were treated by HGF or mesenchymalepithelial transition factor(MET)inhibitor SU11274 in vitro.Cell viability was detected by a Cell Counting Kit-8 assay.Cell proliferation and motility was detected by a bromodeoxyuridine incorporation assay and a wound healing assay,respectively.The expression levels of MET,phosphorylated MET,protein kinase B(AKT),and phosphorylated AKT proteins were determined by Western blot assay.The MET and phosphorylated MET proteins were also determined by immunofluorescence assay.RESULTS:HGF increased ARPE-19 cells’viability,proliferation and migration,and induced an increase of phosphorylated MET and phosphorylated AKT proteins.SU11274 significantly reduced cell viability,proliferation,and migration and decreased the expression of MET and AKT proteins.SU11274 suppressed HGF-induced increase of viability,proliferation,and migration in ARPE-19 cells.Additionally,SU11274 also blocked HGF-induced phosphorylation of MET and AKT proteins.CONCLUSION:HGF enhances cellular viability,proliferation,and migration in RPE cells through the MET/AKT signaling pathway,whereas this enhancement is suppressed by the MET inhibitor SU11274.HGF-induced MET/AKT signaling might be a vital contributor of RPE cells survival.

Expression and significance of pigment epithelium-derived factor and vascular endothelial growth factor in colorectal adenoma and cancer

BACKGROUND The incidence and mortality of colorectal cancer(CRC)are among the highest in the world,and its occurrence and development are closely related to tumor neovascularization.When the balance between pigment epithelium-derived factors(PEDF)that inhibit angiogenesis and vascular endothelial growth factors(VEGF)that stimulate angiogenesis is broken,angiogenesis is out of control,resulting in tumor development.Therefore,it is very necessary to find more therapeutic targets for CRC for early intervention and later treatment.AIM To investigate the expression and significance of PEDF,VEGF,and CD31-stained microvessel density values(CD31-MVD)in normal colorectal mucosa,adenoma,and CRC.METHODS In this case-control study,we collected archived wax blocks of specimens from the Digestive Endoscopy Center and the General Surgery Department of Chengdu Second People's Hospital from April 2022 to October 2022.Fifty cases of specimen wax blocks were selected as normal intestinal mucosa confirmed by electronic colonoscopy and concurrent biopsy(normal control group),50 cases of specimen wax blocks were selected as colorectal adenoma confirmed by electronic colonoscopy and pathological biopsy(adenoma group),and 50 cases of specimen wax blocks were selected as CRC confirmed by postoperative pathological biopsy after inpatient operation of general surgery(CRC group).An immunohistochemical staining experiment was carried out to detect PEDF and VEGF expression in three groups of specimens,analyze their differences,study the relationship between the two and clinicopathological factors in CRC group,record CD31-MVD in the three groups,and analyze the correlation of PEDF,VEGF,and CD31-MVD in the colorectal adenoma group and the CRC group.The F test or adjusted F test is used to analyze measurement data statistically.Kruskal-Wallis rank sum test was used between groups for ranked data.The chi-square test,adjusted chi-square test,or Fisher's exact test were used to compare the rates between groups.All differences between groups were compared using the Bonferroni method for multiple comparisons.Spearman correlation analysis was used to test the correlation of the data.The test level(α)was 0.05,and a two-sided P<0.05 was considered statistically significant.RESULTS The positive expression rate and expression intensity of PEDF were gradually decreased in the normal control group,adenoma group,and CRC group(100%vs 78%vs 50%,χ^(2)=34.430,P<0.001;++~++vs+~++vs-~+,H=94.059,P<0.001),while VEGF increased gradually(0%vs 68%vs 96%,χ^(2)=98.35,P<0.001;-vs-~+vs++~+++,H=107.734,P<0.001).In the CRC group,the positive expression rate of PEDF decreased with the increase of differen-tiation degree,invasion depth,lymph node metastasis,distant metastasis,and TNM stage(χ^(2)=20.513,4.160,5.128,6.349,5.128,P<0.05);the high expression rate of VEGF was the opposite(χ^(2)=10.317,13.134,17.643,21.844,17.643,P<0.05).In the colorectal adenoma group,the expression intensity of PEDF correlated negatively with CD31-MVD(r=-0.601,P<0.001),whereas VEGF was not significantly different(r=0.258,P=0.07).In the CRC group,the expression intensity of PEDF correlated negatively with the expression intensity of CD31-MVD and VEGF(r=-0.297,P<0.05;r=-0.548,P<0.05),while VEGF expression intensity was positively related to CD31-MVD(r=0.421,P=0.002).CONCLUSION It is possible that PEDF can be used as a new treatment and prevention target for CRC by upregulating the expression of PEDF while inhibiting the expression of VEGF.

Regulation role of miR-204 on SIRT1/VEGF in metabolic memory induced by high glucose in human retinal pigment epithelial cells

AIM:To examine the regulatory role of microRNA-204(miR-204)on silent information regulator 1(SIRT1)and vascular endothelial growth factor(VEGF)under highglucose-induced metabolic memory in human retinal pigment epithelial(hRPE)cells.METHODS:Cells were cultured with either normal(5 mmol/L)or high D-glucose(25 mmol/L)concentrations for 8d to establish control and high-glucose groups,respectively.To induce metabolic memory,cells were cultured with 25 mmol/L D-glucose for 4d followed by culture with 5 mmol/L D-glucose for 4d.In addition,exposed in 25 mmol/L D-glucose for 4d and then transfected with 100 nmol/L miR-204 control,miR-204 inhibitor or miR-204 mimic in 5 mmol/L D-glucose for 4d.Quantitative reverse transcription-polymerase chain reaction(RT-qPCR)was used to detect miR-204 mRNA levels.SIRT1 and VEGF protein levels were assessed by immunohistochemical and Western blot.Flow cytometry was used to investigate apoptosis rate.RESULTS:It was found that high glucose promoted miR-204 and VEGF expression,and inhibited SIRT1 activity,even after the return to normal glucose culture conditions.Upregulation of miR-204 promoted apoptosis inhibiting SIRT1 and increasing VEGF expression.However,downregulation of miR-204 produced the opposite effects.CONCLUSION:The study identifies that miR-204 is the upstream target of SIRT1and VEGF,and that miR-204 can protect hRPE cells from the damage caused by metabolic memory through increasing SIRT1 and inhibiting VEGF expression.

Bone morphogenetic protein-6 suppresses TGF-β_(2)-induced epithelial-mesenchymal transition in retinal pigment epithelium

AIM:To evaluate the effect of bone morphogenetic protein-6(BMP-6)on transforming growth factor(TGF)-β_(2)-induced epithelial-mesenchymal transition(EMT)in retinal pigment epithelium(RPE).METHODS:Adult retinal pigment epithelial cell line(ARPE-19)were randomly divided into control,TGF-β_(2)(5μg/L),and BMP-6 small interfering RNA(siRNA)group.The cell morphology was observed by microscopy,and the cell migration ability were detected by Transwell chamber.The EMT-related indexes and BMP-6 protein levels were detected by Western blotting.Furthermore,a BMP-6 overexpression plasmid was constructed and RPE cells were divided into the control group,TGF-β_(2)+empty plasmid group,BMP-6 overexpression group,and TGF-β_(2)+BMP-6 overexpression group.The EMT-related indexes and extracellular regulated protein kinases(ERK)protein levels were detected.RESULTS:Compared with the control group,the migration of RPE cells in the TGF-β_(2) group was significantly enhanced.TGF-β_(2) increased the protein expression levels ofα-smooth muscle actin(α-SMA),fibronectin and vimentin but significantly decreased the protein levels of E-cadherin and BMP-6(P<0.05)in RPE.Similarly,the migration of RPE cells in the BMP-6 siRNA group was also significantly enhanced.BMP-6 siRNA increased the protein expression levels ofα-SMA,fibronectin and vimentin but significantly decreased the protein expression levels of E-cadherin(P<0.05).Overexpression of BMP-6 inhibited the migration of RPE cells induced by TGF-β_(2) and prevented TGF-β_(2) from affecting EMT-related biomarkers(P<0.05).CONCLUSION:BMP-6 prevents the EMT in RPE cells induced by TGF-β_(2),which may provide a theoretical basis for the prevention and treatment of proliferative vitreoretinopathy.

Selective feeding of bay scallop Argopecten irradians on phytoplankton community revealed by HPLC analysis of phytopigments in Bohai Sea, China

Understanding the feeding selectivity on phytoplankton by shellfi sh is currently a big challenge. In order to investigate the feeding behavior of bay scallop ( Argopecten irradians ) on phytoplankton, we compared its compositions of phytopigments in digestive glands with those in the surrounding seawater, and conducted fi ve consecutive investigations between July and November 2016 in a bay scallop culture area along coast of Qinghuangdao City, northwest of the Bohai Sea, China. Phytopigments in four-size fractionated phytoplankton of seawater (micro-(20-200 μm);nano(L)-[10-20 μm];nano(S)-[2.7-10 μm], and pico-[<2.7 μm]) and digestive glands of A . irradians were examined to investigate the selective feeding of A . irradians . Results show that fucoxanthin and peridinin constituted the major part of taxonomically diagnostic carotenoids (TDCs) in the micro- and nano(L)-phytoplankton in seawater. Compared with total phytoplankton biomass of seawater (TPB, sum of the four sizes), a substantial decrease of fucoxanthin proportion to total DCs in digestive glands was observed while that of peridinin, 19′-butanoyloxyfucoxanthin, alloxanthin and 19′-hexanoyloxy-fucoxanthin showed an obvious increase when those pigments were mainly confi ned to micro-sized phytoplankton (20-200 μm). However, zeaxanthin and prasinoxanthin were mainly confi ned to nano(s)- and pico-phytoplankton, of which the proportions in digestive glands were usually lower in TPB. The contribution of lutein to total DCs in digestive glands (with an average of 7.23%) increased compared with TPB of seawater (with an average of 0.63%) during all fi ve sampling times.

Composition of algal pigments in surface freshen layer after ice melt in the central Arctic

Seasonal meltwater input creates a thin freshen layer in surface seawater under ice, which largely shifts the algae assemblages. Our recent observation of photosynthetic pigments in the high Arctic showed that ice bottom and 5 m of seawater under ice contained relatively high concentration of fucoxanthin, while chlorophyll b and lutein were the major diagnostic pigments in ice-water interface and 0 m of seawater under ice. Additionally, a notable change of dominant phytoplankton occurred in the top 5 m of seawater under ice, from chlorophytes-dominated at surface to diatoms-dominated at 5 m depth, which might attribute to the sharp salinity gradient （salinity from 12.5 to 28.1） in the surface seawater under ice. Our results imply that phytoplankton community in surface layer under ice would become more chlorophytes in the future warming Arctic Ocean.

Nanocrystals for enhancement of oral bioavailability of poorly water-soluble drugs

Nanocrystals,a carrier-free colloidal delivery system in nano-sized range,is an interesting approach for poorly soluble drugs.Nanocrystals provide special features including enhancement of saturation solubility,dissolution velocity and adhesiveness to surface/cell membranes.Several strategies are applied for nanocrystals production including precipitation,milling,high pressure homogenization and combination methods such as Nano-Edge^(TM),SmartCrystal and Precipitation-lyophilization-homogenization(PLH)technology.For oral administration,many publications reported useful advantages of nanocrystals to improve in vivo performances i.e.pharmacokinetics,pharmacodynamics,safety and targeted delivery which were discussed in this review.Additionally,transformation of nanocrystals to final formulations and future trends of nanocrystals were also described.

Study on the Pigments of the Colored Cotton

The ecological characteristics and fiber structure of the colored cotton were introduced briefly. The color changing mechanisms of the pigments extracted from colored cottons and some plants were discussed with the results of different experiments, which could offer an academic reference for the color fixations of the colored cotton textile produces and promote the development of the natural colored cotton industry.

Study on the Genetics and Development of Fiber Pigments and Color Deviation After Wetting Process of Naturally Colored Cotton

The genetic control of fiber pigment color in naturally colored cotton was studied. The expression of brown and green fiber color was controlled by incompletely dominant single genes and incompletely dominant major genes, respectively. Production and accumulation of the fiber pigment were related to special expression of enzymatic genes for pigment synthesis in fiber cells. At the stage of fiber lengthening, naturally colored cotton, like white cotton, appeared purely white. But when fiber cell walls entered the thickening stage, pigment appeared by degrees. When the fiber was completely matured (on boll dehiscence), the color reached its darkest level. After wetting process treatment, the hues of the fiber pigment changed in regular patterns. The hue circle for brown and green cotton changed in the opposite direction with wetting process treatment. In general, the treated cotton color and luster became dark and vivid, and this trend provided the possibility for enhancing the fiber quality by suitable environmental friendly finishing. The analysis showed that the color and luster of the cotton may be controlled by a series of pigments which show different chemical performance.

Application of ion chromatography to the determination of water-soluble inorganic and organic ions in atmospheric aerosols

A simple, sensitive and convenient ion chromatography(IC) method was established for the simultaneous determination of twelve water-soluble inorganic anions(F -, Cl -, NO - 2, NO - 3, SO 2- 3, SO 2- 4, PO 3- 4), and fifteen water-soluble organic ions(formate, acetate, MSA, oxalate, malonate, succinate, phthalates, etc.) in atmospheric aerosols. The linear concentrations ranged from 0.005 μg/m 3 to 500 μg/m 3(r = 0.999—0.9999). The relative standard deviation(RSD) were 0.43%—2.00% and the detection limits were from 2.7 ng/m 3 to 88 ng/m 3. The proposed method was successfully applied to the simultaneous determination of those inorganic ions and organic ions in PM 2.5 of Beijing.

Adverse effects of metal exposure on chemotaxis towards water-soluble attractants regulated mainly by ASE sensory neuron in nematode Caenorhabditis elegans

Chemotaxis to water-soluble attractants is mainly controlled by ASE sensory neuron whose specification is regulated by che-1 in Caenorhabditis elegans. Our data suggested that exposure to high concentrations of metals, such as Pb, Cu, Ag, and Cr, would result in severe defects of chemotaxis to water-soluble attractants of NaCl, cAMP, and biotin. Moreover, the morphology of ASE neuron structures as observed by relative fluorescent intensities and relative size of fluorescent puncta of cell bodies, relative lengths of sensory endings in ASE neurons, and the expression patterns of che-1 were obviously altered in metal exposed animals when they meanwhile exhibited obvious chemotaxis defects to water-soluble attractants. In addition, the dendrite morphology could be noticeably changed in animals exposed to 150 μmol/L of Pb, Cu, and Ag. Furthermore, we observed significant decreases of chemotaxis to water-soluble attractants in Pb exposed che-1 mutant at concentrations more than 2.5 μmol/L, and in Cu, Ag, and Cr exposed che-1 mutant at concentrations more than 50 μmol/L. Therefore, impairment of the ASE neuron structures and functions may largely contribute to the appearance of chemotaxis defects to water-soluble attractants in metal exposed nematodes.

On-line Measurement of Water-Soluble Ions in Ambient Particles

Combining the system of rapid collection of ambient particles and ion chromatography, the system of rapid collection of fine particles and ion chromatography （RCFP-IC） was established to automatically analyze on-line the concentrations of water-soluble ions in ambient particles. Here, the general scheme of RCFP-IC is described and its basic performance is tested. The detection limit of RCFP-IC for SO4^2-, NO3^-, NO2^-, Cl^- and F- is below 0.3μg m^-3. The collection efficiency of RCFP-IC increases rapidly with increasing sized particles. For particles larger than 300 nm, the collection efficiency approaches 100%. The precision of RCFP-IC is more than 90% over 28 repetitions. The response of RCFP-IC is very sensitive and no obvious cross-pollution is found during measurement. A comparison of RCFP-IC with an integrated filter measurement indicates that the measurement of RCFP-IC is comparable in both laboratory experiments and field observations. The results of the field experiment prove that RCFP-IC is an effective on-line monitoring system and is helpful in source apportionment and pollution episode monitoring.

Records of bulk organic matter and plant pigments in sediment of the ＂red-tide zone＂ adjacent to the Changjiang River estuary

Cultural eutrophication caused by nutrient over-enrichment in coastal waters will lead to a cascading set of ecosystem changes and deleterious ecological consequences,such as harmful algal blooms(HABs) and hypoxia.During the past two decades since the late 1990s,recurrent large-scale HABs(red tides)and an extensive hypoxic zone have been reported in the coastal waters adjacent to the Changjiang River estuary.To retrieve the history of eutrophication and its associated ecosystem changes,a sediment core was collected from the "red-tide zone" adjacent to the Changjiang River estuary.The core was dated using the^(210)Pb radioisotope and examined for multiple proxies,including organic carbon(OC),total nitrogen(TN),stable isotopes of C and N,and plant pigments.An apparent up-core increase of OC content was observed after the 1970s,accompanied by a rapid increase of TN.The concurrent enrichment of δ^(13)C and increase of the C/N ratio suggested the accumulation of organic matter derived from marine primary production during this stage.The accumulation of OC after the 1970 s well reflected the significant increase of primary production in the red-tide zone and probably the intensification of hypoxia as well.Plant pigments,including chlorophyll a,p-carotene,and diatoxanthin,showed similar patterns of variation to OC throughout the core,which further confirmed the important contribution of microalgae,particularly diatoms,to the deposited organic matter.Based on the variant profiles of the pigments representative of different microalgal groups,the potential changes of the phytoplankton community since the 1970s were discussed.

Effects of Cadmium on Growth, Photosynthetic Pigments, Photosynthetic Performance, Biochemical Parameters and Structure of Chloroplasts in the Agarophyte <i>Gracilaria domingensis</i>(Rhodophyta, Gracilariales)

This paper aimed to evaluate the effects of different concentrations of cadmium on growth rates, photosynthetic pigments, photosynthetic performance, biochemical parameters and structure of chloroplasts in G. domingensis. To accomplish this, apical segments of G. domingensis were cultivated with different concentrations of cadmium, ranging from 100 to 300 μM, over a period of 16 days, and were processed for transmission electron microscopy analysis. The plants exposed to cadmium showed chloroplast alteration, especially degeneration of thylakoids and a decrease in the concentration of photosynthetic pigments, such as chlorophyll a and phycobiliproteins. However, the volume of plastoglobuli increased. As a defense mechanism, the plants treated with cadmium showed an increase in glutathione reductase activity. These results agree with the decreased photosynthetic performance and relative electron transport rate observed after exposure of algae to cadmium. Taken together, these findings strongly indicate that cadmium negatively affects the ultrastructure and metabolism of the agarophyte G. domingensis, thus posing a threat to the economic vitality of this red macroalga.

Preparation of Ultrafine Water-soluble Polymers Nanofiber Mats via Electrospinning

A series of water-soluble polymers such as poly（ethylene oxide）（PEO）, polyacrylamide（PAM） and poly（vinyl pyrrilidone）（PVP） was successfully prepared via the electrospinning of their aqueous solutions without the use of a surfactant. The effects of solution properties on the electrospinning of PEO, PAM and PVP solutions were investigated. The viscosity of the solution, charge density carried by the jet, and the surface tension of the solution are the key factors that influence the morphology and diameter size of the fibers. The viscosity of the solution was measured on a modular compact rheometer. The morphology and the diameter size distribution of the fibers were observed under an environmental scanning electron microscope（ESEM）. The results show that the diameters of the nanofibers electro spun from the solutions of these water soluble polymers were uniform and less than 300 nm.