Understanding the mechanisms underlying biological control of Fusarium diseases in cereals

Many Fusarium species cause serious diseases for cereal cultivation. These include Fusarium head blight and crown rot on wheat and bakanae disease on rice. These represent a major concern both in terms of food security and food safety. The latter is connected with the risk of mycotoxin contamination of grains. Biological control has proven its potential for controlling head blight and crown rot diseases of cereals caused by Fusarium species in a number of studies, and indeed several commercial products are under development. We review current knowledge of the mechanisms underlying biological control with a focus on fungal biocontrol agents, and also include challenges related to co-occurrence of Fusarium species. Several of the established biological control mechanisms (antibiosis, competition, hyperparasitism and induced resistance) can act simultaneously, thus resulting in disease control and, consequently, reduction of mycotoxin contamination. We also review the biological roles of some of the many mycotoxins produced by Fusarium species, and the mechanisms by which they are detoxified by cereal enzymes or by other fungi and how biological control agents (BCAs) can stimulate their degradation. Finally, the effect of biocontrol agents on the resident microbiota, as well as the effect of the resident microbiota on the performances of BCAs, are discussed. New perspectives on the use of biocontrol agents for the management of Fusarium diseases on cereals

Color singlet suppression of quark-gluon plasma formation

The rate of quark-gluon plasma droplet nucleation in superheated hadronic matter is calculated within the MIT bag model. The requirements of color singletness and (to less extent) fixed momentum suppress the nucleation rate by many orders of magnitude, making thermal nucleation of quark-gluon plasma droplets unlikely in ultrarelativistic heavy-ion collisions if the transition is first order and reasonably described by the bag model.Comment: 9 pages, 3 ps figures. To appear in PhysRevC (April 1996

Colour-singlet strangelets at finite temperature

Considering massless $u$ and $d$ quarks, and massive (150 MeV) $s$ quarks in a bag with the bag pressure constant $B^{1/4} = 145$ MeV, a colour-singlet grand canonical partition function is constructed for temperatures $T = 1-30$ MeV. Then the stability of finite size strangelets is studied minimizing the free energy as a function of the radius of the bag. The colour-singlet restriction has several profound effects when compared to colour unprojected case: (1) Now bulk energy per baryon is increased by about $250$ MeV making the strange quark matter unbound. (2) The shell structures are more pronounced (deeper). (3) Positions of the shell closure are shifted to lower $A$-values, the first deepest one occuring at $A=2$, famous $H$-particle ! (4) The shell structure at $A=2$ vanishes only at $T\sim 30$ MeV, though for higher $A$-values it happens so at $T\sim 20$ MeV.Comment: Revtex file(8 pages)+6 figures(ps files) available on request from first Autho

Efficacy of the 1-year (13-cycle) segesterone acetate and ethinylestradiol contraceptive vaginal system : results of two multicentre, open-label, single-arm, phase 3 trials

A ring-shaped, contraceptive vaginal system designed to last 1 year (13 cycles) delivers an average of 0.15 mg segesterone acetate and 0.013 mg ethinylestradiol per day. We evaluated the efficacy of this contraceptive vaginal system and return to menses or pregnancy after use. In two identically designed, multicentre, open-label, single-arm, phase 3 trials (one at 15 US academic and community sites and one at 12 US and international academic and community sites), participants followed a 21-days-in, 7-days-out segesterone acetate and ethinylestradiol contraceptive vaginal system schedule for up to 13 cycles. Participants were healthy, sexually active, non-pregnant, non-sterilised women aged 18-40 years. Women were cautioned that any removals during the 21 days of cyclic use should not exceed 2 h, and used daily paper diaries to record vaginal system use. Consistent with regulatory requirements for contraceptives, we calculated the Pearl Index for women aged 35 years and younger, excluding adjunctive contraception cycles, as the primary efficacy outcome measure. We also did intention-to-treat Kaplan-Meier life table analyses and followed up women who did not use hormonal contraceptives or desired pregnancy after study completion for 6 months for return to menses or pregnancy. The trials are registered with ClinicalTrials.gov, numbers NCT00455156 and NCT00263341. Between Dec 19, 2006, and Oct 9, 2009, at the 15 US sites, and between Nov 1, 2006, and July 2, 2009, at the 12 US and international sites we enrolled 2278 women. Our overall efficacy analysis included 2265 participants (1130 in the US study and 1135 in the international study) and 1303 (57.5%) participants completed up to 13 cycles. The Pearl Index for the primary efficacy group was 2.98 (95% CI 2.13-4.06) per 100 woman-years, and was well within the range indicative of efficacy for a contraceptive under a woman's control. The Kaplan-Meier analysis revealed the contraceptive vaginal system was 97.5% effective, which provided further evidence of efficacy. Pregnancy occurrence was similar across cycles. All 290 follow-up participants reported return to menses or became pregnant (24 [63%] of 38 women who desired pregnancy) within 6 months. Interpretation The segesterone acetate and ethinylestradiol contraceptive vaginal system is an effective contraceptive for 13 consecutive cycles of use. This new product adds to the contraceptive method mix and the 1-year duration of use means that women do not need to return to the clinic or pharmacy for refills every few months78e1054e1064We thank The Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health (NICHD), the US Agency for International Development (USAID), and WHO for funding the phase 3 studies. We also acknowledge all participating study investigators (appendix p 1) and coordinators at the 27 clinical sites for conduct of the two phase 3 clinical trials and the over 2200 women participants from eight countries. We further acknowledge the medical writing assistance of Kathleen Ohleth (Precise Publications; Bedminster. NJ, USA) supported by TherapeuticsMD (Boca Raton, FL, USA). The NICHD (contract no HHSN27500403372) funded and conducted the US study and USAID (grant no GPO-A-00-04-00019-00) funded the international study, which was conducted by the Population Council. WHO Department of Reproductive Health and Research funded two international study sites. Medical writing support for manuscript submission and resubmission was supported by TherapeuticsMD. The authors acknowledge the major contribution of Daniel R Mishell Jr (deceased), from the Department of Obstetrics and Gynecology, University of Southern California, Keck School of Medicine (Los Angeles, CA, USA) who invented the concept of the vaginal system to deliver contraceptive steroids, did many of the clinical studies for the segesterone acetate and ethinylestradiol contraceptive vaginal system, and was a principle investigator for the 300 B phase 3 study analysed in this Article while a member of the International Committee for Contraceptive Research (ICCR) of the Population Council. The authors also gratefully acknowledge the contribution of Horacio B Croxatto, from the University of Chile (Santiago, Chile), who established the clinical centre in Chile, participated in all pivotal clinical studies for this ring, and provided guidance for the full development of this new contraceptive while a member of the ICC