Effects of fungicide on growth of Leptosphaeria maculans and L. biglobosa in relation to development of phoma stem canker on oilseed rape (Brassica napus)

Controlled‐environment and field experiments were done to investigate effects of the fungicide Punch C (flusilazole plus carbendazim) on growth of Leptosphaeria maculans and L. biglobosa in oilseed rape. In controlled‐environment experiments, for plants inoculated with L. maculans, fungicide treatment decreased lesion size and amount of L. maculans DNA in leaves; for plants inoculated with L. biglobosa, fungicide did not affect lesion size or amount of pathogen DNA. When release of ascospores was monitored using a Burkard spore sampler, the timing and pattern of ascospore release differed between the four seasons. In 2006/2007, the majority of ascospores released were L. maculans, whilst in 2007/2008 the majority were L. biglobosa; in both seasons L. maculans ascospores were released before L. biglobosa ascospores. In field experiments in 2002/2003 and 2003/2004, fungicide treatment decreased severity of stem canker on cv. Apex, but gave no significant yield response. In 2006/2007 and 2007/2008, fungicide treatment decreased phoma leaf spot incidence in autumn and stem canker severity at harvest, and increased yield. Fungicide treatment decreased stem canker severity more on cv. Courage, with a good yield response, than on cv. Canberra. In 2002/2003 and 2003/2004, fungicide treatment decreased the frequency of spread of L. maculans into stem pith tissues and in 2006/2007 fungicide decreased the amount of L. maculans DNA in stem tissues (measured by quantitative PCR). These results are used to suggest how effects of fungicides on interactions between L. maculans and L. biglobosa might affect severity of phoma stem canker and yield response.     

Complete genome sequence of Neisseria meningitidis serogroup B strain MC58

The 2,272,351-base pair genome of Neisseria meningitidis strain MC58 (serogroup B), a causative agent of meningitis and septicemia, contains 2158 predicted coding regions, 1158 (53.7%) of which were assigned a biological role. Three major islands of horizontal DNA transfer were identified; two of these contain genes encoding proteins involved in pathogenicity, and the third island contains coding sequences only for hypothetical proteins. Insights into the commensal and virulence behavior of N. meningitidis can be gleaned from the genome, in which sequences for structural proteins of the pilus are clustered and several coding regions unique to serogroup B capsular polysaccharide synthesis can be identified. Finally, N. meningitidis contains more genes that undergo phase variation than any pathogen studied to date, a mechanism that controls their expression and contributes to the evasion of the host immune system.     

The moon: sources of the crustal magnetic anomalies

Previously unmapped Apollo 16 subsatellite magnetometer data collected at low altitudes over the lunar near side are presented. Medium-amplitude magnetic anomalies exist over the Fra Mauro and Cayley Formations (primary and secondary basin ejecta emplaced 3.8 to 4.0 billion years ago) but are nearly absent over the maria and over the craters Copernicus, Kepler, and Reiner and their encircling ejecta mantles. The largest observed anomaly (radial component approximately 21 gammas at an altitude of 20 kilometers) is exactly correlated with a conspicuous light-colored deposit on western Oceanus Procellarum known as Reiner gamma. Assuming that the Reiner gamma deposit is the source body and estimating its maximum average thickness as 10 meters, a minimum mean magnetization level of 5.2 +/- 2.4 x 10(-2) electromagnetic units per gram, or approximately 500 times the stable magnetization component of the most magnetic returned sample, is calculated. An age for its emplacement of 相似文献   

Whole-genome shotgun assembly and analysis of the genome of Fugu rubripes

The compact genome of Fugu rubripes has been sequenced to over 95% coverage, and more than 80% of the assembly is in multigene-sized scaffolds. In this 365-megabase vertebrate genome, repetitive DNA accounts for less than one-sixth of the sequence, and gene loci occupy about one-third of the genome. As with the human genome, gene loci are not evenly distributed, but are clustered into sparse and dense regions. Some "giant" genes were observed that had average coding sequence sizes but were spread over genomic lengths significantly larger than those of their human orthologs. Although three-quarters of predicted human proteins have a strong match to Fugu, approximately a quarter of the human proteins had highly diverged from or had no pufferfish homologs, highlighting the extent of protein evolution in the 450 million years since teleosts and mammals diverged. Conserved linkages between Fugu and human genes indicate the preservation of chromosomal segments from the common vertebrate ancestor, but with considerable scrambling of gene order.     

DNA sequences mediating class switching in alpha-immunoglobulins

Immunoglobulin class switching involves specific DNA rearrangements of the gene segments coding for heavy chain constant regions (CH) during B lymphocyte differentiation. In two different cases of C mu to C alpha switching examined here (T15 and M603) and one taken from the literature (MC101), three different sites on the 5' side of C mu and three different sites on the 5' side of C alpha are joined together in the process of CH switching. The sequences surrounding the three germ-line C alpha sites of recombination are highly conserved blocks of 30 nucleotides that may serve as recognition sequences for CH switching to the C alpha gene. This putative recognition sequence is repeated 17 times in approximately 1400 nucleotides of the germ-line Calpha 5' flanking sequence. The lack of homology between this C alpha sequence and sequences reported for the C gamma 1 and C gamma 2b switch sites suggests that heavy chain switching is mediated by class-specific recognition sequences and, presumably, class-specific regulatory mechanisms. In addition, it appears that in one example (MC101) CH switching progressed from C mu to C alpha to C gamma 1. This switching pathway may present difficulties for the simple deletional model of CH switching.     

Location and chemical synthesis of a binding site for HIV-1 on the CD4 protein

The human immunodeficiency virus type 1 (HIV-1) uses the CD4 protein as a receptor for infection of susceptible cells. A candidate structure for the HIV-1 binding site on the CD4 protein was identified by epitope mapping with a family of eight functionally distinct CD4-specific monoclonal antibodies in conjunction with a panel of large CD4-derived synthetic peptides. All of the seven epitopes that were located reside within two immunoglobulin-like disulfide loops situated between residues 1 and 168 of the CD4 protein. The CD4-specific monoclonal antibody OKT4A, a potent inhibitor of HIV-1 binding, recognized a site between residues 32 and 47 on the CD4 protein. By analogy to other members of the immunoglobulin superfamily of proteins, this particular region has been predicted to exist as a protruding loop. A synthetic analog of this loop (residues 25 to 58) showed a concentration-dependent inhibition of HIV-1-induced cell fusion. It is proposed that a loop extending from residues 37 to 53 of the CD4 protein is a binding site for the AIDS virus.     

Tumor regression by targeted gene delivery to the neovasculature

Efforts to influence the biology of blood vessels by gene delivery have been hampered by a lack of targeting vectors specific for endothelial cells in diseased tissues. Here we show that a cationic nanoparticle (NP) coupled to an integrin alphavbeta3-targeting ligand can deliver genes selectively to angiogenic blood vessels in tumor-bearing mice. The therapeutic efficacy of this approach was tested by generating NPs conjugated to a mutant Raf gene, ATPmu-Raf, which blocks endothelial signaling and angiogenesis in response to multiple growth factors. Systemic injection of the NP into mice resulted in apoptosis of the tumor-associated endothelium, ultimately leading to tumor cell apoptosis and sustained regression of established primary and metastatic tumors.     

A nebular origin for chondritic fine-grained phyllosilicates

Hydrated minerals occur in accretionary rims around chondrules in CM chondrites. Previous models suggested that these phyllosilicates did not form by gas-solid reactions in the canonical solar nebula. We propose that chondrule-forming shock waves in icy regions of the nebula produced conditions that allowed rapid mineral hydration. The time scales for phyllosilicate formation are similar to the time it takes for a shocked system to cool from the temperature of phyllosilicate stability to that of water ice condensation. This scenario allows for simultaneous formation of chondrules and their fine-grained accretionary rims.     

Nonstationary Phase of the Plio-Pleistocene Asian Monsoon

Paleoclimate records indicate that the strength of the Asian summer monsoon is sensitive to orbital forcing at the obliquity and precession periods (41,000 and 23,000 years, respectively) and the extent of Northern Hemisphere glaciation. Over the past 2.6 million years, the timing (phase) of strong monsoons has changed by approximately 83 degrees in the precession and approximately 124 degrees in the obliquity bands relative to the phase of maximum global ice volume (inferred from the marine oxygen isotope record). These results suggest that one or both of these systems is nonstationary relative to orbital forcing.     

An Investigation of Uterine Nitric Oxide Production in Mares Susceptible and Resistant to Persistent Breeding‐Induced Endometritis and the Effects of Immunomodulation

The first objective of this study was to evaluate intrauterine nitric oxide (NO) and endometrial inducible NO synthase (iNOS) in mares susceptible or resistant to persistent breeding‐induced endometritis (PBIE) within 24 h after breeding. Mares susceptible (n = 6) or resistant (n = 6) to PBIE were inseminated over five cycles, and uterine secretions and endometrial biopsies were collected before and 2, 6, 12 and 24 h after insemination. Uterine secretions were analysed for NO and biopsies were analyzed for iNOS expression. A second experiment evaluated the effect of treatment with dexamethasone or mycobacterial cell wall extract (MCWE) on uterine NO production and endometrial iNOS mRNA expression. Six susceptible mares were inseminated over three cycles with (i) killed spermatozoa without treatment (control), (ii) killed spermatozoa with 50 mg of dexamethasone IV or (iii) MCWE IV 24 h prior to insemination with killed spermatozoa. Six resistant mares were inseminated with killed spermatozoa as a control. Six hours after breeding, uterine biopsies and secretions were collected and evaluated for NO and iNOS mRNA. In Experiment 1, resistant mares had an increase in iNOS mRNA expression 2 h post‐breeding compared to baseline (p = 0.045), 12 h (p = 0.014) and 24 h (p = 0.001). Susceptible mares had higher expression 2 h compared to 6 h (p = 0.046). No differences were observed in mRNA or protein expression of iNOS between resistant and susceptible mares. Resistant mares had a relatively steady amount of total intrauterine NO over 24 h, while susceptible mares had an increase over time, with a significantly higher increase in total NO than resistant mares at 6 (p = 0.04) and 12 h (p = 0.032). In Experiment 2, no differences were observed for iNOS mRNA expression. Susceptible mares had increased NO when compared to resistant mares (p = 0.008) and MCWE decreased NO (p = 0.047).