The formation and evolution of flower coloration in Brassica crops.

The flower coloration of Brassica crops possesses significant application and economic value, making it a research hotspot in the field of genetics and breeding. In recent years, great progress has been made in the research on color variation and creation of Brassica crops. However, the underlying molecular mechanisms and evolutional processes of flower colors are poorly understood. In this paper, we present a comprehensive overview of the mechanism of flower color formation in plants, emphasizing the molecular basis and regulation mechanism of flavonoids and carotenoids. By summarizing the recent advances on the genetic mechanism of flower color formation and regulation in Brassica crops, it is clearly found that carotenoids and anthocyanins are major pigments for flower color diversity of Brassica crops. Meantime, we also explore the relationship between the emergence of white flowers and the genetic evolution of Brassica chromosomes, and analyze the innovation and multiple utilization of Brassica crops with colorful flowers. This review aims to provide theoretical support for genetic improvements in flower color, enhancing the economic value and aesthetic appeal of Brassica crops.

Fine mapping and candidate gene analysis of a novel fertility restorer gene for C-type cytoplasmic male sterility in maize (Zea mays L.).

KEY MESSAGE: A novel strong fertility restorer gene Rf12 for C-type cytoplasmic male sterility of maize was finely mapped on chromosome 2. Its best candidate gene Zm00001d007531 is predicted to encode a p-type PPR protein. The lack of strong restorer gene of maize CMS-C greatly limits its application in hybrid seed production. Therefore, the cloning of maize CMS-C novel strong restorer genes is necessary. In this study, a strong restorer line ZH91 for maize CMS-C was found, and the novel restorer gene named Rf12 in ZH91 had been mapped in a 146 kb physical interval on maize chromosome 2. Using the third-generation high-throughput sequencing (ONT), the whole genome sequence of ZH91 was got, and with integrating the annotation information of the reference genome B73_RefGen_v4 and B73_RefGen_v5, four candidate genes were predicted in ZH91 within the mapping region. Then using gene cloning, stranded specific RNA sequencing, qRT-PCR analysis and subcellular localization, Zm00001d007531 was identified as the most likely candidate gene of Rf12. Zm00001d007531 encodes a p-type PPR protein with 19 PPR motifs and targets mitochondria and chloroplast. Stranded specific RNA sequencing and qRT-PCR results both show that the expression of Zm00001d007531 between anthers of near-isogenic lines C478Rf12Rf12 and C478rf12rf12 was significantly difference in pollen mother cell stage. And the result of sequence alignment for Zm00001d007531 gene in 60 materials showed that there are twelve SNPs in CDS region of Zm00001d007531 were tightly linked to the fertility. The finding of a novel strong restorer germplasm resource ZH91 for maize CMS-C can greatly promote the application of maize CMS-C line in maize hybrid seeds production, and the identification of candidate gene Zm00001d007531 can accelerate the backcrossing process of maize CMS-C strong restorer gene Rf12 to some extent.

A semi-continuous efficient strategy for removing phosphorus and nitrogen from eel aquaculture wastewater using the self-flocculating microalga Desmodesmus sp. PW1.

The phosphorus content in eel aquaculture wastewater exceeds the discharge standard, and the amount of wastewater discharged is substantial. Therefore, there is an urgent need to explore an economical and efficient method of treating aquaculture wastewater. This study explored the use of Desmodesmus sp. PW1, a type of microalgae, to treat eel aquaculture wastewater. By optimizing the conditions, Desmodesmus sp. PW1 achieved a total phosphorus (TP) removal efficiency of 92.3%, as well as total nitrogen (TN) and ammonia nitrogen (NH4+-N) removal efficiency of 99%, using a photoperiod of 24:0, a temperature of 25 °C, and an inoculation amount of 15%. Furthermore, Desmodesmus sp. PW1 demonstrated a high self-flocculating efficiency (>90%) within 100 min of settling, which facilitated biomass recovery. Subsequently, a semi-continuous treatment process mode was established with a sewage renewal rate of 90%. The results showed that after four rounds of sewage renewal operations, the microalgae biomass in the sewage treatment system could be maintained between 160.0 and 220.0 mg/L, and the average removal rate of TP was 0.13 mg/(L * h). The lipid content of algae cells collected in the semi-continuous treatment system for eel aquaculture wastewater was as high as 36.5%, and the biodiesel properties met the biodiesel standards authorized by Europe and the United States. Overall, this study provides an economical and effective strategy for converting wastewater into high-value microalgae products.

Preparation, multi-scale structures, and functionalities of acetylated starch: An updated review.

Acetylated starch has been widely used as food additives. However, there was limited information available regarding the impact of acetylation on starch structure and functionalities, as well as the advanced acetylation technologies. This review aimed to summarize current methods for starch acetylation and discuss the structure and functionalities of acetylated starch. Innovative techniques, such as milling, microwave, pulsed electric fields, ultrasonic, and extrusion, could be employed for environmental-friendly synthesis of acetylated starch. Acetylation led to the degradation of starch structures and weakening of the interactions between starch molecules, resulting in the disorganization of starch multi-scale ordered structure. The introduction of acetyl groups retarded the self-reassembly behavior of starch, leading to increased solubility, clarity, and softness of starch-based hydrogels. Moreover, the acetyl groups improved water/oil absorption capacity, emulsifiability, film-forming properties, and colonic fermentability of starch, while reduced the susceptibility of starch molecules to enzymes. Importantly, starch functionalities were largely influenced by the decoration of acetyl groups on starch molecules, while the impact of multi-scale ordered structures on starch physicochemical properties was relatively minor. These findings will aid in the design of structured acetylated starch with desirable functionalities.

Real-time response counterattack strategy of tolerant microalgae Chlorella vulgaris MBFJNU-1 in original swine wastewater and free ammonia.

This work was the first time to systematically clarify the potential tolerance mechanism of an indigenous Chlorella vulgaris MBFJNU-1 towards the free ammonia (FA) during the original swine wastewater (OSW) treatment by transcriptome analysis using C. vulgaris UETX395 as the control group. The obtained results showed that C. vulgaris MBFJNU-1 was found to be more resistant to the high levels of FA (115 mg/L) and OSW in comparison to C. vulgaris UETX395 (38 mg/L). Moreover, the transcriptomic results stated that some key pathways from arginine biosynthesis, electron generation and transmission, ATP synthesis in chloroplasts, and glutathione synthesis of C. vulgaris MBFJNU-1 were greatly related with the OSW and FA. Additionally, C. vulgaris MBFJNU-1 in OSW and FA performed similar results in the common differentially expressed genes from these mentioned pathways. Overall, these obtained results deliver essential details in microalgal biotechnology to treat swine wastewater and high free ammonia wastewater.

Metagenomics analysis of microbial community distribution in large-scale and step-by-step purification system of swine wastewater.

Biological treatment is one of the most widely used methods to treat swine wastewater in wastewater treatment plants. The microbial community plays an important role in the swine slurry treatment system. However, limited information is available regarding the correlation between pollutant concentration and dominant microbial community in swine wastewater. This work aimed to study the profiling of microbial communities and their abundance in the 40 M3/day large-scale and step-by-step treatment pools of swine wastewater. Metagenome sequencing was applied to study the changes of microbial community structure in biochemical reaction pools. The results showed that in the heavily polluted pools, it was mainly Proteobacteria, Cyanobacteria, Chlorella and other strains that could tolerate high concentration of ammonia nitrogen to remove nitrogen and absorb chemical oxygen demand (COD). In the moderately polluted pools, Nitrospirae, Actinobacteria and other strains further cooperated to purify swine wastewater. In the later stage, the emergence of Brachionus indicated the reduction of water pollution. The dominant microbes and their abundance changed with the purification of swine wastewater in different stages. Moreover, the dominant microflora of swine wastewater treatment pools at all levels reflected little difference in phylum classification level, while in genus classification level, the dominant microflora manifested great difference. Findings demonstrated that the microorganisms maintained ecological balance and absorbed the nutrients in the swine wastewater treatment pools, so as to play the role of purifying sewage. Therefore, the stepwise purification of swine wastewater can be realized by adding bacteria and microalgae of different genera.

Physiological attributes and transcriptomics analyses reveal the mechanism response of Helictotrichon virescens to low temperature stress.

BACKGROUND: Helictotrichon virescens is a perennial grass that is primarily distributed in high altitude areas of 2000 ~ 4500 m. It is widely cultivated in the Qinghai-Tibet Plateau of China, strongly resistant to cold, and an essential part of the wild herbs in this region. However, the molecular mechanism of the response of H. virescens to low temperature stress and the key regulatory genes for specific biological processes are poorly understood. RESULTS: Physiological and transcriptome analyses were used to study the cold stress response mechanism in H virescens. During the low temperature stress period, the content of chlorophyll a and b decreased more and more with the delay of the treatment time. Among them, the difference between the controls was not significant, and the difference between the control and the treatment was significant. At the same time, the expression of related differential genes was up-regulated during low temperature treatment. In addition, the plant circadian pathway is crucial for their response to cold stress. The expression of differentially expressed genes that encode LHY and HY5 were strongly up-regulated during cold stress. CONCLUSIONS: This study should help to fully understand how H. virescens responds to low temperatures. It answers pertinent questions in the response of perennial herbs to cold stress, i.e., how light and low temperature signals integrate to regulate plant circadian rhythms and Decrease of content of chlorophylls (which can be also accompanied with decrease of total quantity of reaction centers) leads to an increase in photosynthetic damage.

A novel two-stage heterotrophic cultivation for starch-to-protein switch to efficiently enhance protein content of Chlorella sp. MBFJNU-17.

This work aimed to firstly establish an efficient and novel two-stage cultivation process to produce microalgal biomass rich in protein using a heterotrophic Chlorella sp. MBFJNU-17 strain. In the first-stage cultivation, to reduce the glucose and urea utilization, microalga achieved a high biomass at 40 g/L glucose and 1 g/L urea; meantime, the expression from starch biosynthesis genes of microalga was up-regulated under nitrogen-starvation conditions for starch accumulation (55.01%). In the second-stage cultivation, based on the over-compensation effect, Chlorella cells after the first-stage cultivation were further treated at 5 g/L glucose and 3 g/L urea to up-regulate starch degradation, central carbon metabolism and urea absorption genes expression to drive intracellular starch-to-protein switch for biosynthetic protein (59.75%). Moreover, microalga performed similar characteristics in a 10-L fermenter by the established process. Taken together, Chlorella sp. MBFJNU-17 was the promising candidate to produce high-value biomass enriched in protein by the established two-stage cultivation.

An integrated semi-continuous culture to treat original swine wastewater and fix carbon dioxide by an indigenous Chlorella vulgaris MBFJNU-1 in an outdoor photobioreactor.

This work was the first time to evaluate the ability of an isolated Chlorella vulgaris MBFJNU-1 to remove nutrients of original swine wastewater (OSW) and fix carbon dioxide (CO2) under outdoor conditions in a simultaneous manner using column photobioreactors. The results showed that microalga cultivated at 3% CO2 in a batch mode achieved the highest biomass and CO2 fixation rate. Then, a semi-continuous process for OSW treatment and CO2 fixation simultaneously by microalga was established and the renewal rate of this process was deeply investigated. Microalga cultivated at 3% CO2 and 80% renewal rate gave the highest productivities of total biomass, CO2 fixation and the greatest average removal rates of total nitrogen, N-NH4+, total phosphorus and chemical oxygen demand. Taken together, C. vulgaris MBFJNU-1 was the promising microalga under outdoor conditions for swine wastewater treatment and CO2 fixation simultaneously for biofuels and biofertilizer production.

The characterization and candidate gene isolation for a novel male-sterile mutant ms40 in maize.

KEY MESSAGE: A novel genic male-sterile mutant ms40 was obtained from EMS treated RP125. The key candidate gene ZmbHLH51 located on chromosome 4 was identified by map-based cloning. This study further enriched the male sterile gene resources for both production applications and theoretical studies of abortion mechanisms. Maize male-sterile mutant 40 (ms40) was obtained from the progeny of the ethyl methanesulfonate (EMS) treated inbred line RP125. Genetic analysis indicated that the sterility was controlled by a single recessive nuclear gene. Cytological observation of anthers revealed that the cuticles of ms40 anthers were abnormal, and no Ubisch bodies were observed on the inner surface of ms40 anthers through scanning electron microscopy(SEM). Moreover, its tapetum exhibited delayed degradation and then blocked the formation of normal microspores. Using map-based cloning strategy, the ms40 locus was found to locate in a 282-kb interval on chromosome 4, and five annotated genes were predicted within this region. PCR-based sequencing detected a single non-synonymous SNP (G > A) that changed glycine (G) to arginine (A) in the seventh exon of Zm00001d053895, while no sequence difference between ms40 and RP125 was found for the other four genes. Zm00001d053895 encodes the bHLH transcription factor ZmbHLH51 which is localized in the nucleus. Phylogenetic analysis showed that ZmbHLH51 had the highest homology with Sb04g001650, a tapetum degeneration retardation (TDR) bHLH transcription factor in Sorghum bicolor. Co-expression analysis revealed a total of 1192 genes co-expressed with ZmbHLH51 in maize, 647 of which were anther-specific genes. qRT-PCR results suggested the expression levels of some known genes related to anther development were affected in ms40. In summary, these findings revealed the abortion characteristics of ms40 anthers and lay a foundation for further studies on the mechanisms of male fertility.

Substitution Mapping of the Major Quantitative Trait Loci Controlling Stigma Exsertion Rate from Oryza glumaepatula.

BACKGROUND: Stigma exsertion rate (SER) is a key determinant for the outcrossing ability of male sterility lines (MSLs) in hybrid rice seed production. In the process of domestication, the outcrossing ability of cultivated rice varieties decreased, while that of wild Oryza species kept strong. Here, we detected the quantitative trait loci (QTLs) controlling SER using a set of single-segment substitution lines (SSSLs) derived from O. glumaepatula, a wild Oryza species. RESULTS: Seven QTLs for SER were located on 5 chromosomes. qSER-1a and qSER-1b were located on chromosome 1. qSER-3a and qSER-3b were mapped on chromosome 3, and qSER-3b was further located at an estimated interval of 898.8 kb by secondary substitution mapping. qSER-5, qSER-9 and qSER-10 were identified on chromosomes 5, 9 and 10, respectively, and qSER-9 was delimited to an estimated region of 551.9 kb by secondary substitution mapping. The additive effects of the 7 QTLs ranged from 10.6% to 14.8%, which were higher than those of most loci for SER reported previously. CONCLUSIONS: qSER-1a and qSER-1b are novel loci for SER on chromosome 1. All of the 7 QTLs have major effects on SER. The major QTLs of SER will help to develop MSLs with strong outcrossing ability.

qRf8-1, a Novel QTL for the Fertility Restoration of Maize CMS-C Identified by QTL-seq.

C-type cytoplasmic male sterility (CMS-C), one of the three major CMS types in maize, has a promising application prospect in hybrid seed production. However, the complex genetic mechanism underlying the fertility restoration of CMS-C remains poorly understood. The maize inbred line A619 is one of the rare strong restorer lines carrying the restorer gene Rf4, but different fertility segregation ratios are found in several F2 populations derived from crosses between isocytoplasmic allonucleus CMS-C lines and A619. In the present study, the segregation ratios of fertile to sterile plants in the (CHuangzaosi × A619) F2 and BC1F1 populations (36.77:1 and 2.36:1, respectively) did not follow a typical monogenic model of inheritance, which suggested that some F2 and BC1F1 plants displayed restored fertility even without Rf4 To determine the hidden locus affecting fertility restoration, next-generation sequencing-based QTL-seq was performed with two specific extreme bulks consisting of 30 fertile and 30 sterile rf4rf4 individuals from the F2 population. A major QTL related to fertility restoration, designated qRf8-1, was detected on the long arm of chromosome 8 in A619. Subsequently, qRf8-1 was further validated and narrowed down to a 17.93-Mb genomic interval by insertion and deletion (InDel) and simple sequence repeat (SSR) marker-based traditional QTL mapping, explaining 12.59% (LOD = 25.06) of the phenotypic variation. Thus, using genetic analyses and molecular markers, we revealed another fertility restoration system acting in parallel with Rf4 in A619 that could rescue the male sterility of CHuangzaosi. This study not only expands the original fertility restoration system but also provides valuable insights into the complex genetic mechanisms underlying the fertility restoration of CMS-C.

Nutrients removal from piggery wastewater coupled to lipid production by a newly isolated self-flocculating microalga Desmodesmus sp. PW1.

A newly isolated microalgal strain, Desmodesmus sp. PW1, possessing not only high potential for removing nitrogen and phosphorous from piggery wastewater but excellent self-flocculating ability, was provided here. Strain PW1 grew well in diluted and undiluted piggery wastewater, and could effectively remove total nitrogen and total phosphorus with removal rates up to 90% and 70%, respectively. In the laboratory scale by 30-L photobioreactor, microalga also performed well in TN (65.3%) and TP (83.5%) removal. Strain PW1 cultivated in the stationary phase achieved high self-flocculating efficiency (>90%) in 2.5 h of settling; meanwhile, temperature and pH slightly influenced on the flocculation. The potential mechanism on self-flocculation was considered related to hydrophobic extracellular polymeric substances. Furthermore, the fatty acid compositions of PW1 were mainly hexadecanoic acid, oleic acid and linoleic acid. Taken together, Desmodesmus sp. PW1 was the promising candidate to overcome the microalgae harvesting problem in piggery wastewater treatment.

Continuous Production of Ursodeoxycholic Acid by Using Two Cascade Reactors with Co-immobilized Enzymes.

Ursodeoxycholic acid (UDCA) is an effective drug for the treatment of hepatitis. In this study, 7α-hydroxysteroid dehydrogenase (7α-HSDH) and lactate dehydrogenase (LDH), as well as 7ß-hydroxysteroid dehydrogenase (7ß-HSDH) and glucose dehydrogenase (GDH), were co-immobilized onto an epoxy-functionalized resin (ES-103) to catalyze the synthesis of UDCA from chenodeoxycholic acid (CDCA). Through optimizing the immobilization pH, time, and loading ratio of enzymes to resin, the specific activities of immobilized LDH-7αHSDH@ES-103 and 7ßHSDH-GDH@ES-103 were 43.2 and 25.8 U g-1 , respectively, which were 12- and 516-fold higher than that under the initial immobilization conditions. Continuous production of UDCA from CDCA was subsequently achieved by using immobilized LDH-7αHSDH@ES-103 and 7ßHSDH-GDH@ES-103 in two serial packed-bed reactors. The yield of UDCA reached nearly 100 % and lasted for at least 12 h in the packed-bed reactors, which was superior to that of the batchwise reaction. This efficient continuous approach developed herein might provide a feasible route for large-scale biotransformation of CDCA into UDCA.

Protein Engineering and Homologous Expression of Serratia marcescens Lipase for Efficient Synthesis of a Pharmaceutically Relevant Chiral Epoxyester.

The lipase isolated from Serratia marcescens (LipA) is a useful biocatalyst for kinetic resolution of a pharmaceutically relevant epoxyester, (±)-3-(4'-methoxyphenyl) glycidic acid methyl ester [(±)-MPGM], to afford optically pure (-)-MPGM, a key intermediate for the synthesis of diltiazem hydrochloride. Two mutants, LipAL315S and LipAS271F, were identified from the combinatorial saturation mutation library of 14 amino acid residues lining the substrate-binding pocket. LipAL315S, LipAS271F, and their combination LipAL315S/S271F showed 2.6-, 2.2-, and 4.6-fold improvements in their specific activities towards para-nitrophenyl butyrate (pNPB), respectively. Among these positive mutants, LipAS271F displayed a 3.5-fold higher specific activity towards the pharmaco substrate (±)-MPGM. Kinetic study showed that the improvement in catalytic efficiency of LipAS271F against (±)-MPGM was mainly resulted from the enhanced affinity between substrate and enzyme, as indicated by the decrease of K m. Furthermore, to address the insoluble expression issue in Escherichia coli, the homologous expression of LipA gene in S. marcescens was achieved by introducing it into an expression vector pUC18, resulting in ca. 20-fold higher lipase production. The significantly improved volumeric production and specific activity of S. marcescens lipase make it very attractive as a new-generation biocatalyst for more efficient and economical manufacturing of (-)-MPGM.

Engineering 7ß-Hydroxysteroid Dehydrogenase for Enhanced Ursodeoxycholic Acid Production by Multiobjective Directed Evolution.

Ursodeoxycholic acid (UDCA) is the main active ingredient of natural bear bile powder with multiple pharmacological functions. 7ß-Hydroxysteroid dehydrogenase (HSDH) is a key biocatalyst for the synthesis of UDCA. However, all the 7ß-HSDHs reported commonly suffer from poor activity and thermostability, resulting in limited productivity of UDCA. In this study, a multiobjective directed evolution (MODE) strategy was proposed and applied to improve the activity, thermostability, and pH optimum of a 7ß-HSDH. The best variant (V3-1) showed a specific activity 5.5-fold higher than and a half-life 3-fold longer than those of the wild type. In addition, the pH optimum of the variant was shifted to a weakly alkaline value. In the cascade reaction, the productivity of UDCA with V3-1 increased to 942 g L-1 day-1, in contrast to 141 g L-1 day-1 with the wild type. Therefore, this study provides a useful strategy for improving the catalytic efficiency of a key enzyme that significantly facilitated the bioproduction of UDCA.

Enzymatic transformation of vina-ginsenoside R7 to rare notoginsenoside ST-4 using a new recombinant glycoside hydrolase from Herpetosiphon aurantiacus.

An eco-friendly and convenient preparation method for notoginsenoside ST-4 has been established by completely transforming vina-ginsenoside R7 using a recombinant glycosidase hydrolyzing enzyme (HaGH03) from Herpetosiphon aurantiacus. This enzyme specifically hydrolyzed the glucose at the C-20 position but not the external xylose or two inner glucoses at position C-3. Protein sequence BLAST revealed that HaGH03, composed of 749 amino acids and presumptively listed as a member of the family 3 glycoside hydrolases, has highest identity (48 %) identity with a thermostable ß-glucosidase B, which was not known of any functions for ginsenoside transformation. The steady state kinetic parameters for purified HaGH03 measured against p-nitrophenyl ß-D-glucopyranoside and vina-ginsenoside R7 were K M = 5.67 ± 0.24 µM and 0.59 ± 0.23 mM, and k cat = 69.2 ± 0.31/s and 2.15 ± 0.46/min, respectively. HaGH03 converted 2.5 mg/mL of vina-ginsenoside R7 to ST-4 with a molar yield of 100 % and a space-time yield of 104 mg/L/h in optimized conditions. These results underscore that HaGH03 has much potential for the effective preparation of target ginsenosides possessing valuable pharmacological activities. This is the first report identifying an enzyme that has the ability to transform vina-ginsenoside R7 and provides an approach to preparing rare notoginsenoside ST-4.

[Effect of HIF-1α and its mechanism on invasion and metastasis of esophageal carcinoma Eca109 cells in vitro and in vivo].

AIM: To investigate the effects of HIF-1α by RNAi on invasion and metastasis of esophageal carcinoma Eca109 cells in vitro and in vivo, in order to explore its probable mechanism. METHODS: CoCl(2); was used to mimic tumor hypoxic microenvironment. mRNA and protein levels of HIF-1α, E-cadherin and MMP-2 under hypoxia were detected by RT-PCR and immunohistochemistry. The effects of silencing HIF-1α by RNAi on HIF-1α, E-cadherin and MMP-2 mRNA were detected by RT-PCR. The effect of RNAi on invasion and metastasis were tested by cell scratch assay and transwell chambers. The Eca109-implanted nude mouse model was established, and the effects of HIF-1αon tumor growth and lymphoid node metastasis were observed. The expressions of HIF-1α, E-cadherin and MMP-2 in transplanted tumors were detected by Western blot, and the effects of HIF-1α on tumor growth, invasion and metastasis in vitro and in vivo were analyzed. RESULTS: Hypoxia up-regulated HIF-1α protein, mRNA and protein levels of E-cadherin down-regulated, and MMP-2 up-regulated, while had no effect on HIF-1α mRNA . RNAi could silencing HIF-1α effectively, and inhibited E-cadherin or MMP-2 decreased or increased, respectively. The migration and the number of invading cells decreased (P<0.05) after silencing HIF-1α by RNAi. The tumor volume was much smaller, lymph node metastasis rate lower as well in vivo (P<0.05). CONCLUSION: Via its effects on E-cadherin and MMP-2, HIF-1α regulate the growth, invasion and metastasis of Eca109 cells in vitro and in vivo.

Dosimetric evaluation of conventional radiotherapy, 3-D conformal radiotherapy and direct machine parameter optimisation intensity-modulated radiotherapy for breast cancer after conservative surgery.

INTRODUCTION: The use of conservative surgery combined with whole-breast irradiation (WBI) has been established as a valid alternative to mastectomy for the management of early-stage breast cancer. The aim of this study was to compare dosimetric parameters of the planning target volume(PTV) and organs at risk (OARs) between conventional radiation therapy (CR), 3-D conformal radiation therapy (3DCRT), and direct machine parameter optimisation intensity-modulated radiation therapy (DMPO-IMRT) after breast-conserving surgery. METHODS AND MATERIALS: Computed tomography (CT) scans from 20 patients (13 left-sided and 7 right-sided) previously treated with T1N0 or ductal carcinoma were selected for this dosimetric planning study. We designed CR, 3DCRT and DMPO-IMRT plans for each patient. The prescribed dose was 50 Gy/2 Gy/25 f, 95% of PTV received the prescription dose. Doses were computed with a commercially available treatment planning system using convolution/superimposition (CS) algorithm. Plans were compared according to dose-volume histogram (DVH) analysis in terms of PTV homogeneity and conformity indices (HI and CI) as well as OARs dose and volume parameters. RESULTS: Both the HI and CI of the PTV showed statistically significant difference between CR, 3DCRT and DMPO-IMRT with those of DMPO-IMRT were best (P < 0.05). Compared with CR, 3DCRT showed smaller exposed volumes of ipsilateral lung, contralateral breast and heart while DMPO-IMRT indicated larger exposed volumes of ipsilateral lung (except for V20 and V30), contralateral breast and heart. In addition, DMPO-IMRT demonstrated an increase of exposed volume of ipsilateral lung (except for V30), contralateral breast and heart compared with 3DCRT. CONCLUSIONS: In WBI of breast cancer after conservative surgery, 3DCRT and DMPO-IMRT improved the homogeneity and conformity of the PTV compared with CR. Meanwhile, 3DCRT reduced the irradiated volumes of OARs at all dose levels listed in our study while DMPO-IMRT reduced the irradiated volumes of OARs in high-dose areas but increased the irradiated volumes of OARs in low-dose areas.

RAPD and internal transcribed spacer sequence analyses reveal Zea nicaraguensis as a section Luxuriantes species close to Zea luxurians.

Genetic relationship of a newly discovered teosinte from Nicaragua, Zea nicaraguensis with waterlogging tolerance, was determined based on randomly amplified polymorphic DNA (RAPD) markers and the internal transcribed spacer (ITS) sequences of nuclear ribosomal DNA using 14 accessions from Zea species. RAPD analysis showed that a total of 5,303 fragments were produced by 136 random decamer primers, of which 84.86% bands were polymorphic. RAPD-based UPGMA analysis demonstrated that the genus Zea can be divided into section Luxuriantes including Zea diploperennis, Zea luxurians, Zea perennis and Zea nicaraguensis, and section Zea including Zea mays ssp. mexicana, Zea mays ssp. parviglumis, Zea mays ssp. huehuetenangensis and Zea mays ssp. mays. ITS sequence analysis showed the lengths of the entire ITS region of the 14 taxa in Zea varied from 597 to 605 bp. The average GC content was 67.8%. In addition to the insertion/deletions, 78 variable sites were recorded in the total ITS region with 47 in ITS1, 5 in 5.8S, and 26 in ITS2. Sequences of these taxa were analyzed with neighbor-joining (NJ) and maximum parsimony (MP) methods to construct the phylogenetic trees, selecting Tripsacum dactyloides L. as the outgroup. The phylogenetic relationships of Zea species inferred from the ITS sequences are highly concordant with the RAPD evidence that resolved two major subgenus clades. Both RAPD and ITS sequence analyses indicate that Zea nicaraguensis is more closely related to Zea luxurians than the other teosintes and cultivated maize, which should be regarded as a section Luxuriantes species.