虫草成熟子囊壳、子囊与子囊孢子的电镜观察

虫草子囊壳壁为拟薄壁组织,基部与子座菌丝相联,顶端有一孔口,其内无缘丝,中心腔内无侧丝,基部着生的子囊垂直平行排列。子囊顶端中央是乳状突起,围以隆起的环状膜质边缘。成熟时,其顶端乳状突起膨大,膜质边缘也随之翻卷,中央有一小孔。同一子囊壳内子囊顶端发育阶段不同,说明子囊的形成不同步。子囊内含有两条平行的具横隔的子囊孢子。虫草子囊顶端形态结构即不象虫草属模式种蛹虫草,也不象头状虫草,说明子囊顶端的形态结构的种间差异。     

康定虫草主要寄主斜脉蝠蛾的研究

冬虫夏草是一味名贵的中药材.四川康定虫草的主要寄主斜脉蝠蛾翅面色斑多变异,可区分成“黑白斑”和“黄毛斑”两大色斑型.经交配试验和成虫形态特征(触角、口器、翅脉、前足、雌雄外生殖器和鳞片的超微结构等)的观察,证明为同一种,经鉴定是斜脉蝠蛾(Hepialus oblifurcus Chu et Wang)^**.     

冬虫夏草模式标本的研究

对冬虫夏草Ｃｏｒｄｙｃｅｐｓｓｉｎｅｎｓｉｓ（Ｂｅｒｋ．）Ｓａｃｃ．的模式标本进行了形态学和有关文献的研究,井与近邻的同种标本进行了比较;该模式现存英国皇家植物园,邱国标本馆,系１８７９年由Ｍ．Ｊ．Ｂｅｒｋｅｌｅｙ研究的标本。     

Transformation of the rice blast fungus Magnaporthe grisea to benomyl resistance

A transformation method based on a dominant selectable marker (benomyl resistance) was developed for the rice blast fungus Magnaporthe grisea. The heterologous gene for -tubulin from Neurospora crassa (pBT3) was used to obtain benomyl-resistant M. grisea transformants at a frequency of 20 to 30/g of DNA. Control transformations carried out with a plasmid conferring hygromycin resistance or a derivative of pBT3 containing a repetitive DNA sequence, yielded the same frequency of transformation as that of pBT3. Molecular analysis of the transformants indicated multiple integration of the vector DNA.     

SOBIR1 and AGB1 independently contribute to nonhost resistance to Pyricularia oryzae (syn. Magnaporthe oryzae) in Arabidopsis thaliana

ABSTRACT

Rice blast caused by Pyricularia oryzae (syn. Magnaporthe oryzae) is a disease devastating to rice. We have studied the Arabidopsis-P. oryzae pathosystem as a model system for nonhost resistance (NHR) and found that SOBIR1, but not BAK1, is a positive regulator of NHR to P. oryzae in Arabidopsis. AGB1 is also involved in NHR. However, the genetic interactions between SOBIR1, BAK1, and AGB1 are uncharacterized. In this study, we delineated the genetic interactions between SOBIR1, BAK1, and AGB1 in NHR to P. oryzae in Arabidopsis and found SOBIR1 and AGB1 independently control NHR to P. oryzae in Arabidopsis pen2-1 mutant plants. Furthermore, XLG2, but not TMM, has a positive role in penetration resistance to P. oryzae in Arabidopsis pen2-1 mutant plants. Our study characterized genetic interactions in Arabidopsis NHR.

Abbreviations: PRR: pattern recognition receptor, RLK: receptor-like kinase, RLP: receptor-like protein, BAK1: BRASSINOSTEROID INSENSITIVE 1-ASSOCIATED RECEPTOR KINASE 1, BIR1: BAK1-INTERACTING RECEPTOR-LIKE KINASE 1, SOBIR1: SUPPRESSOR OF BIR1-1-1, AGB1: ARABIDOPSIS G PROTEIN ß-SUBUNIT 1, XLG2: EXTRA-LARGE G PROTEIN 2     

Effect of Metalaxyl on the incidence and severity of Pearl millet downy mildew disease in Northern Nigeria

Pearl millet downy mildew (DM) incidence, severity and yield losses of two pearl millet varieties (local and improved) due to the disease were determined in the field. Significant differences in the disease incidence and severity were recorded in the plots sown with metalaxyl-treated seeds and those sown with non-treated seeds, indicating the efficacy of the fungicide on the fungus. Yield losses due to non-treatment of seeds with metalaxyl was 40.88 and 45.39% in a local variety and 43.00 and 18.60% in an improved variety in the 2000 and 2001 cropping seasons respectively. Significant differences between plots sown with metalaxyl-treated and those sown with non-treated seeds were obtained for other yield components such as 1000-grains weight, panicle length and weight.     

Chemical and Physicochemical Properties of Phytase from Aspergillus terreus

Some chemical and physicochemical properties of the purified phytase preparation produced by Asp. terreus were investigated. From the results of the examination of amino acid analysis, it was suggested that there existed some components other than amino acids in the purified enzyme. Examination of the neutral sugar analysis, therefore, was made by gaschromatography, and it was found that the purified enzyme preparation contained mannose, galactose and a small amount of inositol.

The molecular weight of the enzyme was found to be 214,000 by the Archibald method, and 2.2~2.3×10⁵ by gel-filtration on a Sephadex G–200 column. It was found that by guanidine hydrochloride or by urea, the purified enzyme preparation was dissociated into only one kind of subunit. The native enzyme was supposed to be a homohexamer of the subunits whose molecular weight is 37,000.     

Guanosine Diphosphate Mannose in Conformational Relation to Other Suger Nucleotides and Phosphates in Solution

Molecular conformational transition of GDPMan and solution conformation of α-d- mannopyranose moiety in Man-l-P and GDPMan were examined in relation to other sugar nucleotides and phosphates. GDPMan and other sugar nucleotides examined revealed changes in the optical rotation in sigmoidal curve in water by addition of urea. The change was reversible without significant decomposition and is attributable to dissociation of an ordered form into a random form. Optical conformational values in 8m urea solution were+116° for GDPMan, +58°~+79° for UDPGlc, +79° for UDPGal, +135°~+143° for UDPGlcNAc, and +138°~ +155° for UDPGIcA.

NMR analysis and periodate oxidation study revealed the ⁴C₁ conformation of α-d-hexopyranose moieties in Man-1-P, Glc-l-P, GDPMan, UDPGlcNAc and UDPGalNAc.     

The Nutritional Value of D-Amino Acid in the Chick Nutrition

The nutritional values of 16 D-amino acids in chick growth were studied on the purified diets containing crystalline amino acids as a sole source of nitrogen. Growth rate, feed consumption and nitrogen retention were measured. The nutritional values of D-amino acids were studied by comparing individually with the control groups fed on the diet containing all L-amino acids and negative control groups fed with the diet omitted the corresponding L-isomer. The following results were obtained. Essential amino acids: 1. Equal or almost equal nutritional value to the corresponding L-isomer; methionine, phenylalanine, leucine, proline. 2. Half nutritional value compared with L-isomer; valine. 3. Small nutritional value compared with L-isomer; tryptophan, isoleucine, histidine. 4. No nutritional value; lysine, threonine, arginine. Non-essential amino acid: 1. Equal or almost equal nutritional value to the corresponding L-isomer; serine, tyrosine, cystine. 2. There is a possibility that it has a slight growth retardation effect; alanine. 3. The growth retardation effect was found; aspartic acid.     

Induction of Chlorosis,ROS Generation and Cell Death by a Toxin Isolated from Pyricularia oryzae

The ethyl acetate extract of the conidia germination fluid from an Avena isolate (Br58) of Pyricularia oryzae had chlorosis-inducing activity on oat leaf segments. The same activity was also present in the acetone extract of an oatmeal agar culture of Br58. Fungal cultures were used for a large-scale preparation. A series of acetone and ethyl acetate extraction monitored by chromatography was used to isolate an active fraction. The active principle was purified by HPLC. We show by NMR and LC/MS that the toxin was an oxidized C18 unsaturated fatty acid named Mag-toxin. Mag-toxin induced chlorosis on oat leaf segments incubated in the light but not in the dark. Reactive oxygen species (ROS) and cell death were induced by Mag-toxin in oat cells. The sub-cellular localization of ROS generation induced by the toxin treatment was correlated with the location of mitochondria. Interestingly, the induction of ROS generation and cell death by Mag-toxin was light-independent.