WHITE STRIPE LEAF8, encoding a deoxyribonucleoside kinase, is involved in chloroplast development in rice.

KEY MESSAGE: WSL8 encoding a deoxyribonucleoside kinase (dNK) that catalyzes the first step in the salvage pathway of nucleotide synthesis plays an important role in early chloroplast development in rice. The chloroplast is an organelle that converts light energy into chemical energy; therefore, the normal differentiation and development of chloroplast are pivotal for plant survival. Deoxyribonucleoside kinases (dNKs) play an important role in the salvage pathway of nucleotides. However, the relationship between dNKs and chloroplast development remains elusive. Here, we identified a white stripe leaf 8 (wsl8) mutant that exhibited a white stripe leaf phenotype at seedling stage (before the four-leaf stage). The mutant showed a significantly lower chlorophyll content and defective chloroplast morphology, whereas higher reactive oxygen species than the wild type. As the leaf developed, the chlorotic mutant plants gradually turned green, accompanied by the restoration in chlorophyll accumulation and chloroplast ultrastructure. Map-based cloning revealed that WSL8 encodes a dNK on chromosome 5. Compared with the wild type, a C-to-G single base substitution occurred in the wsl8 mutant, which caused a missense mutation (Leu 349 Val) and significantly reduced dNK enzyme activity. A subcellular localization experiment showed the WSL8 protein was targeted in the chloroplast and its transcripts were expressed in various tissues, with more abundance in young leaves and nodes. Ribosome and RNA-sequencing analysis indicated that some components and genes related to ribosome biosynthesis were down-regulated in the mutant. An exogenous feeding experiment suggested that the WSL8 performed the enzymic activity of thymidine kinase, especially functioning in the salvage synthesis of thymidine monophosphate. Our results highlight that the salvage pathway mediated by the dNK is essential for early chloroplast development in rice.

DS1/OsEMF1 interacts with OsARF11 to control rice architecture by regulation of brassinosteroid signaling.

BACKGROUND: Plant height and leaf angle are important determinants of yield in rice (Oryza sativa L.). Genes involved in regulating plant height and leaf angle were identified in previous studies; however, there are many remaining unknown factors that affect rice architecture. RESULTS: In this study, we characterized a dwarf mutant named ds1 with small grain size and decreased leaf angle,selected from an irradiated population of ssp. japonica variety Nanjing35. The ds1 mutant also showed abnormal floral organs. ds1 plants were insensitive to BL treatment and expression of genes related to BR signaling was changed. An F2 population from a cross between ds1 and indica cultivar 93-11 was used to fine map DS1 and to map-based clone the DS1 allele, which encoded an EMF1-like protein that acted as a transcriptional regulator. DS1 was constitutively expressed in various tissues, and especially highly expressed in young leaves, panicles and seeds. We showed that the DS1 protein interacted with auxin response factor 11 (OsARF11), a major transcriptional regulator of plant height and leaf angle, to co-regulate D61/OsBRI1 expression. These findings provide novel insights into understanding the molecular mechanisms by which DS1 integrates auxin and brassinosteroid signaling in rice. CONCLUSION: The DS1 gene encoded an EMF1-like protein in rice. The ds1 mutation altered the expression of genes related to BR signaling, and ds1 was insensitive to BL treatment. DS1 interacts with OsARF11 to co-regulate OsBRI1 expression.

Brassinosteroid (BR) biosynthetic gene lhdd10 controls late heading and plant height in rice (Oryza sativa L.).

KEY MESSAGE: A Brd2 allele suppresses heading date by altering the expression of heading date regulators such as OsMADS50 , and also negatively regulates chlorophyll biosynthesis. Heading date and plant height are important determinants of yield in rice (Oryza sativa L.). In this study, we characterized a late heading, dwarf mutant known as lhdd10 selected following ethyl methane sulfonate (EMS)-treatment of ssp. indica cultivar 93-11. lhdd10 showed late heading, dwarfness and slightly darker-green leaves than wild-type 93-11 under long-day and short-day conditions. We isolated lhdd10 by map-based cloning; it encoded a putative FAD-linked oxidoreductase protein (a brassinosteroid biosynthetic gene) that localized to the nucleus. LHDD10 was constitutively expressed in various tissues, but more so in shoot apices and panicles. Our data showed that lhdd10 influences heading date by controlling the expression of heading date regulators, such as OsMADS50 in both LD and SD conditions. lhdd10 also negatively regulated expression of chlorophyll biosynthetic genes to reduce the chlorophyll content. Our data indicated that BRs play important roles in regulating heading date and chlorophyll biosynthesis. This work provides material that will allow study of how BRs regulate heading date in rice.

A detailed analysis of the leaf rolling mutant sll2 reveals complex nature in regulation of bulliform cell development in rice (Oryza sativa L.).

Bulliform cells are large, thin-walled and highly vacuolated cells, and play an important role in controlling leaf rolling in response to drought and high temperature. However, the molecular mechanisms regulating bulliform cell development have not been well documented. Here, we report isolation and characterisation of a rice leaf-rolling mutant, named shallot-like 2 (sll2). The sll2 plants exhibit adaxially rolled leaves, starting from the sixth leaf stage, accompanied by increased photosynthesis and reduced plant height and tiller number. Histological analyses showed shrinkage of bulliform cells, resulting in inward-curved leaves. The mutant is recessive and revertible at a rate of 9%. The leaf rolling is caused by a T-DNA insertion. Cloning of the insertion using TAIL-PCR revealed that the T-DNA was inserted in the promoter region of LOC_Os07 g38664. Unexpectedly, the enhanced expression of LOC_Os07 g38664 by the 35S enhancer in the T-DNA is not responsible for the leaf rolling phenotype. Further, the enhancer also exerted a long-distance effect, including up-regulation of several bulliform cell-related genes. sll2 suppressed the outward leaf rolling of oul1 in the sll2oul1 double mutant. We conclude that leaf rolling in sll2 could be a result of the combined effect of multi-genes, implying a complex network in regulation of bulliform cell development.

Retrospective study of the impact of fellowship training on two quality and safety measures in uterine artery embolization.

RATIONALE AND OBJECTIVES: To measure the impact of 1-year interventional fellowship training on fluoroscopic time and contrast media utilization in uterine artery embolization (UAE). MATERIALS AND METHODS: Retrospective single institution analysis of 323 consecutive UAEs performed by 12 interventional fellows using a standardized protocol. Fluoroscopy time and contrast media volume were recorded for each patient and correlated with stage of fellowship training. Preprocedure uterine volume (using MRI or ultrasound) was used as a measure of procedural complexity. Regression analysis was conducted per trainee factoring in duration of training, procedure number, supervising radiologist, uterine volume, and outcome variables of fluoroscopy time and contrast media volume. RESULTS: Median number of patients treated per trainee was 27 (range, 16-43) with mean fluoroscopic time 24.5 minutes (range, 4-90 min) and mean contrast volume 190 mL (range, 50-320 mL). Increasing uterine volume had no significant effect (P > .05) on fluoroscopic time but significantly increased (P < .001) contrast media volume. Significant training effect was identified with decrease in fluoroscopic time (P < .001) and decrease in contrast volume (P = .02) over training. Over the course of a 1-year fellowship, these summed to a decrease of 12 minutes in UAE fluoroscopy time and 17 mL less contrast. CONCLUSION: A significant (P < .05) training effect that is clinically relevant was demonstrated over the course of a yearlong interventional radiology fellowship program in performance of a standardized protocol for UAE. This data supports fellowship training as a basis for UAE credentialing and privileging.

Heading date gene, dth3 controlled late flowering in O. Glaberrima Steud. by down-regulating Ehd1.

Heading date in rice is an important agronomic trait controlled by several genes. In this study, flowering time of variety Dianjingyou 1 (DJY1) was earlier than a near-isogenic line (named NIL) carried chromosome segment from African rice on chromosome 3S, when grown in both long-day (LD) and short-day (SD) conditions. By analyzing a large F2 population from NIL × DJY1, the locus DTH3 (QTL for days to heading on chromosome 3) controlling early heading date in DJY1 was fine mapped to a 64-kb segment which contained only one annotated gene, a MIKC-type MADS-box protein. We detected a 6-bp deletion and a single base substitution in the C-domain by sequencing DTH3 in DJY1 compared with dth3 in NIL, and overexpression of DTH3 caused early flowering in callus. Quantitative real-time PCR revealed that the transcript level of dth3 in NIL was lower than that DTH3 in DJY1 in both LD and SD conditions. The Early heading date 1 (Ehd1) which promotes the RFT1, was up-regulated by DTH3 in both LD and SD conditions. Based on Indel and dCAPs marker analysis, the dth3 allele was only present in African rice accessions. A phylogenetic analysis based on microsatellite genotyping suggested that African rice had a close genetic relationship to O. rufipogon and O. latifolia, and was similar to japonica cultivars. DTH3 affected flowering time and had no significant effect on the main agronomic traits.

Molecular analysis of an additional case of hybrid sterility in rice (Oryza sativa L.).

Hybrid sterility hinders the exploitation of the heterosis displayed by japonica × indica rice hybrids. The variation in pollen semi-sterility observed among hybrids between the japonica recipient cultivar and each of two sets of chromosome segment substitution lines involving introgression from an indica cultivar was due to a factor on chromosome 5 known to harbor the gene S24. S24 was fine mapped to a 42 kb segment by analyzing a large F(2) population bred from the cross S24-NIL × Asominori, while the semi-sterility shown by the F(1) hybrid was ascribable to mitotic failure at the early bicellular pollen stage. Interestingly, two other pollen sterility genes (f5-Du and Sb) map to the same region (Li et al. in Chin Sci Bull 51:675-680, 2006; Wang et al. in Theor Appl Genet 112:382-387, 2006), allowing a search for candidate genes in the 6.4 kb overlap between the three genes. By sequencing the overlapped fragment in wild rice, indica cultivars and japonica cultivars, a protein ankyrin-3 encoded by the ORF2 was identified as the molecular base for S24. A cultivar Dular was found to have a hybrid-sterility-neutral allele, S24-n, in which an insertion of 30 bp was confirmed. Thus, it was possible to add one more case of molecular bases for the hybrid sterility. No gamete abortion is caused on heterozygous maternal genotype with an impaired sequence from the hybrid-sterility-neutral genotype. This result will be useful in understanding of wide compatibility in rice breeding.

Imaging of giant cell tumour of the tendon sheath.

Giant cell tumours of the tendon sheath (GCTTS) and pigmented villonodular synovitis (PVNS) are part of a spectrum of benign proliferative lesions of synovial origin that may affect the joints, bursae and tendon sheaths. This review article describes the clinicopathological features and imaging findings in patients with GCTTS. GCTTS usually presents as a soft tissue mass with pressure erosion of the underlying bone. Magnetic resonance (MR) imaging of GCTTS typically shows low to intermediate signal on T1- and T2-weighted spin-echo sequences due to the presence of haemosiderin, which exerts a paramagnetic effect. On gradient-echo sequences, the paramagnetic effect of haemosiderin is further exaggerated, resulting in areas of very low signal due to the blooming artefact. Ultrasonography shows a soft mass related to the tendon sheath that is hypervascular on colour or power Doppler imaging.

Identification of stably expressed quantitative trait loci for cooked rice elongation in non-Basmati varieties.

The elongation of the cooked grain determines the cooking and eating quality of Basmati rice. The identification of stable quantitative trait loci (QTLs), especially those from non-Basmati types, will extend the genetic basis of the Basmati type and facilitate the breeding of high-quality varieties. A set of recombinant inbred lines derived from an indica x japonica hybrid was used to identify QTLs controlling the elongation ratio (ER), elongation index (EI), and water absorption (WA) of the cooked grain. Three ER QTLs on chromosomes 2, 4, and 12, two EI QTLs on chromosomes 2 and 5, and two WA QTLs on chromosomes 2 and 6 were detected. Four of these QTLs were validated using a set of established chromosome segment substitution lines. The genetic effect of qER-2 was explored in an analysis of segregating generations, using 8 newly developed simple sequence repeat markers. Two tightly linked loci (qER-2a and qER-2b) were identified on chromosome 2.

Therapeutic effects of Sophora moorcroftiana alkaloids in combination with albendazole in mice experimentally infected with protoscolices of Echinococcus granulosus

The objective of the present study was to determine if the combination of alkaloids from Sophora moorcroftiana seeds and albendazole might be effective in the treatment of experimental echinococcosisin female NIH mice (6 weeks old and weighing 18-20 g, N = 8 in each group) infected withprotoscolices of Echinococcus granulosus. Viable protoscolices (N = 6 x 103) were cultured in vitro in 1640 medium and mortality was calculated daily. To determine the in vivo efficacy, mice were inoculated intraperitoneally with viable protoscolices and then treated once daily by gavage for three months with the alkaloids (50 mg kg-1 day-1) and albendazole (50 mg kg-1 day-1), separately and in combination (both alkaloids at 25 mg kg-1 day-1 and albendazole at 25 mg kg-1 day-1). Next, the hydatid cysts collected from the peritoneal cavity of the animals were weighed and serum IL-4, IL-2, and IgE levels were analyzed. Administration of alkaloids to cultured protoscolices showed significant dose- and time-dependent killing effects. The weight of hydatid cysts was significantly decreased upon treatment with each drug (P < 0.01), but the decrease was more prominent and the rate of hydatid cyst growth inhibition was much higher (76.1 percent) in the group receiving the combined treatments (18.3 ± 4.6 mg). IL-4 and total IgE were decreased (939 ± 447 pg/mL and 2.03 ± 0.42 IU/mL, respectively) in serum from mice treated with alkaloids and albendazole compared with the untreated control (1481 ± 619 pg/mL and 3.31 ± 0.37 IU/mL; P < 0.01). These results indicate that S. moorcroftiana alkaloids have protoscolicidal effects and the combination of alkaloids and albendazole has significant additive effects.

Therapeutic effects of Sophora moorcroftiana alkaloids in combination with albendazole in mice experimentally infected with protoscolices of Echinococcus granulosus.

The objective of the present study was to determine if the combination of alkaloids from Sophora moorcroftiana seeds and albendazole might be effective in the treatment of experimental echinococcosisin female NIH mice (6 weeks old and weighing 18-20 g, N = 8 in each group) infected withprotoscolices of Echinococcus granulosus. Viable protoscolices (N = 6 x 10(3)) were cultured in vitro in 1640 medium and mortality was calculated daily. To determine the in vivo efficacy, mice were inoculated intraperitoneally with viable protoscolices and then treated once daily by gavage for three months with the alkaloids (50 mg kg-1 day-1) and albendazole (50 mg kg-1 day-1), separately and in combination (both alkaloids at 25 mg kg-1 day-1 and albendazole at 25 mg kg-1 day-1). Next, the hydatid cysts collected from the peritoneal cavity of the animals were weighed and serum IL-4, IL-2, and IgE levels were analyzed. Administration of alkaloids to cultured protoscolices showed significant dose- and time-dependent killing effects. The weight of hydatid cysts was significantly decreased upon treatment with each drug (P < 0.01), but the decrease was more prominent and the rate of hydatid cyst growth inhibition was much higher (76.1%) in the group receiving the combined treatments (18.3 +/- 4.6 mg). IL-4 and total IgE were decreased (939 +/- 447 pg/mL and 2.03 +/- 0.42 IU/mL, respectively) in serum from mice treated with alkaloids and albendazole compared with the untreated control (1481 +/- 619 pg/mL and 3.31 +/- 0.37 IU/mL; P < 0.01). These results indicate that S. moorcroftiana alkaloids have protoscolicidal effects and the combination of alkaloids and albendazole has significant additive effects.

The genetic basic and fine-mapping of a stable quantitative-trait loci for aluminium tolerance in rice.

Aluminium (Al) toxicity is a primary cause of low rice productivity in acid soils. We have mapped a number of quantitative-trait loci (QTL) controlling Al tolerance in a recombinant inbred line population derived from a cross between the tolerant japonica cultivar Asominori and the sensitive indica cultivar IR24. Tolerance was assessed on the basis of relative root elongation. QTL were detected on chromosomes 1, 9, and 11, with the percentages of phenotypic variance explained ranging from 13.5 to 17.7%. Alleles from Asominori at all three QTL were associated with increased Al tolerance. qRRE-9 is expressed both in the genetic background of IR24 and in an Asominori/IR24-mixed background. qRRE-9 was reduced to the single recessive Mendelian factor Alt-9. High-resolution genetic and physical maps were constructed for Alt-9 in a BC(3)F(2) population of 1,043 individuals. Alt-9 maps between RM24702 and ID47-2 on chromosome 9, and co-segregates with RM5765.

Fine mapping of S31, a gene responsible for hybrid embryo-sac abortion in rice (Oryza sativa L.).

Partial abortion of female gametes and the resulting semi-sterility of indica x japonica inter-subspecific rice hybrids have been ascribed to an allelic interaction, which can be avoided by the use of wide compatibility varieties. To further understand the genetic mechanism of hybrid sterility, we have constructed two sets of hybrids, using as male parent either the typical japonica variety Asominori, or the wide compatibility variety 02428; and as female, a set of 66 chromosome segment substitution lines in which various chromosomal segments from the indica variety IR24 have been introduced into a common genetic background of Asominori. Spikelet semi-sterility was observed in hybrid between CSSL34 and Asominori, which is known to carry the sterility gene S31 (Zhao et al. in Euphytica 151:331-337, 2006). Cytological analysis revealed that the semi-sterility of the CSSL34 x Asominori hybrid was caused primarily by partial abortion of the embryo sac at the stage of the mitosis of the functional megaspore. A population of 1,630 progeny of the three-way cross (CSSL34 x 02428) x Asominori was developed to map S31. Based on the physical location of linked molecular markers, S31 was thereby delimited to a 54-kb region on rice chromsome 5. This fragment contains eight predicted open reading frames, four of which encode known proteins and four putative proteins. These results are relevant to the map-based cloning of S31, and the development of marker-assisted transfer of non-sterility allele inducing alleles to breeding germplasm, to allow for a more efficient exploitation of heterosis in hybrid rice.

QTL analysis for rice grain length and fine mapping of an identified QTL with stable and major effects.

Grain length in rice plays an important role in determining rice appearance, milling, cooking and eating quality. In this study, the genetic basis of grain length was dissected into six main-effect quantitative trait loci (QTLs) and twelve pairs of epistatic QTLs. The stability of these QTLs was evaluated in four environments using an F7 recombinant inbred line (RIL) population derived from the cross between a Japonica variety, Asominori, and an Indica variety, IR24. Moreover, chromosome segment substitution lines (CSSLs) harboring each of the six main-effect QTLs were used to evaluate gene action of QTLs across eight environments. A major QTL denoted as qGL-3a, was found to express stably not only in the isogenic background of Asominori but also in the recombinant background of Asominori and IR24 under multiple environments. The IR24 allele at qGL-3a has a positive effect on grain length. Based on the test of advanced backcross progenies, qGL-3a was dissected as a single Mendelian factor, i.e., long rice grain was controlled by a recessive gene gl-3. High-resolution genetic and physical maps were further constructed for fine mapping gl-3 by using 11 simple sequence repeat (SSR) markers designed using sequence information from seven BAC/PAC clones and a BC4F2 population consisting of 2,068 individuals. Consequently, the gl-3 gene was narrowed down to a candidate genomic region of 87.5 kb long defined by SSR markers RMw357 and RMw353 on chromosome 3, which provides a basis for map-based cloning of this gene and for marker-aided QTL pyramiding in rice quality breeding.

Genetic dissection of silicon uptake ability in rice (Oryza sativa L.).

The adequate presence of silicon (Si) in rice plants can enhance their yield and improve their tolerance to various biotic and abiotic stresses. In this study Si uptake abilities were compared between the japonica rice cultivar (cv.) Kinmaze and the indica rice cv. DV85 under three Si concentrations (0.16, 0.4, and 1.6mM) at different time points from 1 to 12h. The results showed that the phenotypic values of two traits-Si uptake by individual plants (SP, Si uptake by all roots of a plant) and Si uptake per unit root dry weight (SR=SP/root dry weight)-of Kinmaze were significantly higher than those of DV85 (P<0.01). Meanwhile, a kinetic study indicated that the Si transporters in Kinmaze and DV85 had the same affinity for silicic acid, but with different Vmax values, indicating that Kinmaze had more Si transporters in the roots than DV85. This may be the main reason for the difference in Si uptake ability between Kinmaze and DV85. In addition, a mapping population consisting of 81 recombinant inbred lines (RILs) derived from the cross between Kinmaze and DV85 was used to detect quantitative trait loci (QTLs) underlying SP and SR. The RILs follow a continuous one-peak distribution and show transgressive segregation in both directions for SP, SR, and root dry weight (RDW). Three QTLs for SP, four for SR, and three for RDW were detected. This can explain 7.16-17.15% of the phenotypic variation (PVE). Thus, the results obtained in this study provide a better understanding of the mechanism of rice Si uptake ability and the basis for fine-mapping the genes involved.

Stability of QTLs for rice grain dimension and endosperm chalkiness characteristics across eight environments.

Rice appearance quality, including traits specifying grain dimension and endosperm chalkiness, represents a major problem in many rice-producing areas of the world. In this study, the genetic basis of six appearance quality traits of milled rice was dissected into quantitative trait loci (QTL) main effects, and the stability of these QTLs was assessed in a population of 66 chromosome segment substitution lines (CSSLs) across eight environments. The CSSLs showed transgressive segregation for many of the traits, and significant correlations were detected among most of the traits. Twenty-two QTLs were identified on eight chromosomes, and numerous QTLs affecting related traits were mapped in the same regions, probably reflecting pleiotropic effects. Nine QTLs, namely qGL-1,qGL-3, qGW-5,qLWR-3, qLWR-5,qPGWC-8, qPGWC-9, qACE-8, and qDEC-8, were consistently detected across the eight environments. The additive main effect and multiplicative interaction (AMMI) analysis showed that genotype (G) x environment (E) interaction was significant for all six traits, with the first three iPCA terms accounting for over 80% of the G x E variance. Both D(I) values and the iPCA1-iPCA2 biplots showed that the CSSLs harboring the nine QTL alleles were more stable than those carrying any of the additional 13 QTL alleles, thereby confirming their environmental stability and pointing to their appropriateness as targets for marker-assisted selection for high-quality rice varieties.

QTL detection for eating quality of cooked rice in a population of chromosome segment substitution lines.

The genetic mechanism underlying six palatability properties of cooked rice and three physico-chemical traits was dissected in 66 BC(3)F(2) chromosome segment substitution lines (CSSLs), using a complete linkage map in three successive years. The CSSLs showed transgressive segregation for all traits studied. Significant correlation was detected among most palatability traits. A total of 25 QTLs for the nine traits were identified on nine chromosomes, and many QTLs affecting different quality traits were mapped in the same regions. Six QTLs--qLT-8 for luster, qTD-6 and qTD-8 for tenderness, qIVOE-6 and qIVOE-8 for integrated value of organoleptic evaluation, and qAC-8 for amylose content--were repeatedly detected across the 3 years. Phenotypic values were significantly different between the recurrent parent, cultivar Asominori, and the CSSLs harboring any of the six QTL alleles across the three environments, indicating that these six QTLs were non-environment-specific and could be used for marker-assisted selection in rice quality improvement.

[Analysis of heading time genotype for a rice male sterile line Zhenshan 97A].

Zhenshan 97A, a rice male sterile, were applied widely since the release of hybrid rice in 1973 in China, but the genotype of heading time in this sterile line was still unknown. This definitely limited the further use of this sterile line in breeding practice and re-production of hybrid seeds. To solve this problem, we analyzed the segregation pattern of phenotype of heading time in progenies from crosses between Zhenshan 97A and four tester cultivars, Akihikari (e1e1e2e2e3e3 Se-1eSe-1e), Koshihikari (E1E1E2E2e3e3Se-1eSe-1e), Nipponbare (E1E1e2e2e3e3Se-1Se-1) and Hinohikari (E1E1E2E2e3e3Se-1Se-1), whose genotypes of heading time were already known. The results showed that the genotype of heading time in Zhenshan 97A was e1e1e2e2E3E3Se-1Se-1 and it also carried a recessive inhibitor i-Se-1 for phtoperiod-sensitivity. Meanwhile, a major photoperiod-sensitive dominant genes Se-1 and other modified photoperiod-sensitive genes: i-Se-1, E3, Hd3(En-Se-1), Hd5 and Hd6, were identified in Zhenshan 97A by crossing with QTL nearly isogenic lines: NIL (Hd1), NIL (Hd2), NIL(Hd3), NIL(Hd5) and NIL(Hd6).

Eicosapentaenoic acid modulates cyclin expression and arrests cell cycle progression in human leukemic K-562 cells.

Eicosapentaenoic acid (EPA) is a polyunsaturated fatty acid (20:5omega3) found primarily in aquatic organisms. We have shown previously that EPA inhibits the growth but is not toxic to human leukemic K-562 cells. In this study, the anti-proliferative effect of EPA on the leukemic cells was further determined and its impacts on cell cycle progression and cyclin expression were investigated. EPA inhibited proliferation of K-562 cells, which was associated with accumulation of G0/G1 cells and down-regulation of cyclin E expression. Cyclin B1-expressing cells were also reduced showing that down-regulation of cyclin expression might be important in the anti-proliferation of EPA.

Induction of apoptosis by dietary polyunsaturated fatty acids in human leukemic cells is not associated with DNA fragmentation.

Apoptosis is important in anticancer strategy. In this study, bivariate annexin V/PI flow cytometry showed that dietary polyunsaturated fatty acids, arachidonic acid (AA) and eicosapentaenoic acid (EPA), induced apoptosis in human leukemic HL-60 but not K-562 cells. Results from DNA-PI flow cytometry and TUNEL flow cytometry illustrated that neither AA nor EPA induced DNA fragmentation in the leukemic cells. These findings suggested that the AA- and EPA-induced apoptosis might not associate with endonucleases activation, and DNA fragmentation could not be used as a sole criterion to identify apoptotic cells.