Characterization of cell structural change,growth, lipid accumulation,and pigment profile of a novel oleaginous microalga, <Emphasis Type="Italic">Vischeria stellata</Emphasis> (Eustigmatophyceae), cultured with different initial nitrate supplies

The appropriate microalgal species and the optimal nitrogen supply in culture medium are vital factors in maximizing biomass and metabolite productivities in microalgae. Vischeria stellata is an edaphic unicellular eustigmatophycean microalga. Cytological and ultrastructural characteristics and the effects of different initial nitrate-nitrogen concentrations on growth, lipid accumulation, fatty acid profile, and pigment composition were investigated in the present study. The cell structures of V. stellata changed with the degree of nutrient utilization and growth phase. The initial nitrate concentration for the optimal growth of V. stellata ranged from 6.0 to 9.0 mM. The maximum total lipid (TLs), neutral lipid (NLs), and total fatty acid (TFAs) contents were 55.9, 51.9, and 44.7 % of dry biomass, respectively. The highest volumetric productivity of TLs, NLs, and TFAs reached 0.28, 0.25, and 0.21 g L^?1 day^?1, respectively. V. stellata had a suitable fatty acid profile for biodiesel production, as well as containing eicosapentaenoic acid (EPA) for nutraceutical applications. In addition, the content β-carotene, increased gradually as culture time was prolonged, resulting in its exclusive production at the end of cultivation. V. stellata is a promising microalgal strain for the production of biofuels and bioproducts.     

Improving of lipid productivity of the biodiesel promising green microalga <Emphasis Type="Italic">Chlorella pyrenoidosa</Emphasis> via low-energy ion implantation

High lipid content in microalgae is an essential parameter for adopting of microalgal biomass as a feedstock for biodiesel. Mutation is one approach to obtain desired algal strain with high lipid production. In this study, a mutant strain of Chlorella pyrenoidosa was isolated using 1.5?×?10¹⁵ ions cm^?2 s^?1 of N⁺ ion beam implantation technique, which has been widely used in mutagenesis of agricultural crops. N⁺ implantation slightly improved the growth of the mutant over the corresponding wild strain with significant increase in lipid content (32.4 % higher than the wild strain), which resulted in significant increase in lipid productivity by 35 %. In addition, ion implantation mutagenesis of C. pyrenoidosa resulted in 21.4 % decrease in total saturated fatty acids (SFAs) compared to the wild type, with a noticeable increase in polyunsaturated fatty acids (PUFAs). The increase in PUFAs was due mainly to stimulation of hexadecadienoic acid (C16:2) and octadecadienoic acid (C18:2) production. However, the SFA content of wild and mutant strains was 31.7 and 24.9 % of total fatty acids, respectively, highlighting the oxidative stability of biodiesel produced by both strains according to the European standards. Cultivation of C. pyrenoidosa mutant in selenite enrichment medium for five successive cultivation experiments showed insignificant changes in biomass productivity, lipid content, and lipid productivity alongside the study period, which confirms the genetic stability of the produced mutant. The present study confirmed the feasibility of generation of microalgae mutants with significant high lipid production using ion beam implantation.     

Morphological,Molecular and Pathological Characterization of Phytophthora amaranthi sp. nov. from Amaranth in Taiwan

In the spring of 2007, a serious disease on amaranth was noticed in several farms in the major amaranth production area in central Taiwan. Abundant oospores were found in the disease tissues. A species of Phytophthora was consistently isolated from disease tissues. The organism formed abundant oospores with smooth walls and with amphigynous antheridia in single culture. Sporangia were partially deciduous with short‐ to medium‐length pedicels. Morphological characteristics of this organism did not match any reported Phytophthora species, and the organism was named Phytophthora amaranthi. Pathogenicity tests and molecular characterization confirmed the identity of the organism as a new pathogen of amaranth and a new species of Phytophthora.     

A Cocktail ELISA Semi‐nested RT‐PCR Assay to Detect Bean pod mottle virus in Soya bean Seeds

Bean pod mottle virus (BPMV) has been identified as an important pathogen for plant quarantine in China because large quantities of soya bean seeds (approximately 7 × 10⁷ tons) are imported annually. To develop a practical detection programme for BPMV, a cocktail enzyme‐linked immunosorbent assay (ELISA) nested RT‐PCR using a combination of serological and molecular methods was designed for soya bean seeds. The single‐vessel detection assay was performed in a 96‐well ELISA plate, which served as a carrier for the subsequent nested RT‐PCR assay. Assay specificity was demonstrated by the production of the expected 330‐ and 296‐bp bands using the external and internal primers, respectively. This method was 10⁴‐fold more sensitive than immunocapture‐RT‐PCR (IC‐RT‐PCR). In particular, it is important to note that this assay resulted in successful micro‐extraction from soya bean seeds and combined the advantages of each individual technique. The cocktail ELISA nested RT‐PCR is a specific, sensitive, rapid and economical procedure to rapidly identify and characterize BPMV and could be suitable for both primary‐level platforms and laboratories.     

小叶兜兰的果实生长和雌配子体发育

为了解濒危兰科植物小叶兜兰(Paphiopedilum barbigerum Tang et Wang)胚珠和雌配子体的发育过程,采用常规石蜡切片技术对其果实的生长动态进行了研究。结果表明,授粉后60~75 d的蒴果内种子数量迅速增加,到授粉后120 d时种子充满整个蒴果。授粉后40 d的胎座上分化形成多数由1层表皮细胞包被1列细胞的胚珠原基;授粉后60 d时位于胎座指状结构末端处紧靠表皮细胞下方的孢原细胞分化为大孢子母细胞。之后,大孢子母细胞经过减数分裂和有丝分裂最终形成成熟胚囊;授粉后135 d胚囊发育成熟,附着在胎座上的种子个体分化明显。小叶兜兰胚囊的发育类型为双孢子葱型,胚珠为倒生胚珠,薄珠心,单珠被,成熟胚囊为8核。这为小叶兜兰的生殖生物学及繁殖体系的建立提供理论依据。     

怀宁毛茛, 安徽毛茛科一新种

描述了发现自安徽的毛茛科毛茛属一新种,怀宁毛茛。此新种与猫爪草在亲缘关系上甚为相近,与后者的区别在于本种的植株具丝形,有块根的匍匐茎,具三出复叶的基生叶的二侧生小叶分裂成二不等大的小叶,心皮的花柱比子房稍短或与子房等长。     

水稻短根突变体Osksr5的遗传分析和基因定位

水稻根系对其生长、发育及产量等起着至关重要的作用。该研究从甲基磺酸乙酯（ethyl methane sulfonate,EMS）诱变的籼稻Kasalath突变体库中筛选到1个根系变短的突变体,命名为Osksr5（Oryza sativa kasalath short root 5）,该突变体植株具体表现为主根、不定根和侧根都明显变短,不定根的数目相对减少,株高与野生型相比也明显矮小。遗传分析结果表明,该突变性状由1对隐性核基因控制。利用图位克隆技术将OsKSR5基因定位在第1染色体的STS（sequence tagged site）分子标记33027k和33471k,物理距离约为444 kb。对OsKSR5基因的定位为进一步克隆该基因和阐明水稻根系发育的分子机理奠定了基础。     

TrkB Promotes Breast Cancer Metastasis via Suppression of Runx3 and Keap1 Expression

In metastatic breast cancer, the acquisition of malignant traits has been associated with the increased rate of cell growth and division, mobility, resistance to chemotherapy, and invasiveness. While screening for the key regulators of cancer metastasis, we observed that neurotrophin receptor TrkB is frequently overexpressed in breast cancer patients and breast cancer cell lines. Additionally, we demonstrate that TrkB expression and clinical breast tumor pathological phenotypes show significant correlation. Moreover, TrkB expression was significantly upregulated in basal-like, claudin-low, and metaplastic breast cancers from a published microarray database and in patients with triple-negative breast cancer, which is associated with a higher risk of invasive recurrence. Interestingly, we identified a new TrkB-regulated functional network that is important for the tumorigenicity and metastasis of breast cancer. We demonstrated that TrkB plays a key role in regulation of the tumor suppressors Runx3 and Keap1. A markedly increased expression of Runx3 and Keap1 was observed upon knockdown of TrkB, treatment with a TrkB inhibitor, and in TrkB kinase dead mutants. Additionally, the inhibition of PI3K/AKT activation significantly induced Runx3 and Keap1 expression. Furthermore, we showed that TrkB enhances metastatic potential and induces proliferation. These observations suggest that TrkB plays a key role in tumorigenicity and metastasis of breast cancer cells through suppression of Runx3 or Keap1 and that it is a promising target for future intervention strategies for preventing tumor metastasis and cancer chemoprevention.