DYNAMICS ANALYSIS OF A DELAYED HIV INFECTION MODEL WITH CTL IMMUNE RESPONSE AND ANTIBODY IMMUNE RESPONSE

In this paper,dynamics analysis of a delayed HIV infection model with CTL immune response and antibody immune response is investigated.The model involves the concentrations of uninfected cells,infected cells,free virus,CTL response cells,and antibody antibody response cells.There are three delays in the model:the intracellular delay,virus replication delay and the antibody delay.The basic reproductive number of viral infection,the antibody immune reproductive number,the CTL immune reproductive number,the CTL immune competitive reproductive number and the antibody immune competitive reproductive number are derived.By means of Lyapunov functionals and LaSalle’s invariance principle,sufficient conditions for the stability of each equilibrium is established.The results show that the intracellular delay and virus replication delay do not impact upon the stability of each equilibrium,but when the antibody delay is positive,Hopf bifurcation at the antibody response and the interior equilibrium will exist by using the antibody delay as a bifurcation parameter.Numerical simulations are carried out to justify the analytical results.

Open ADAMTS13 Promotes the Cross-Linking of Von Willebrand Factor Molecules

Von Willebrand factor(VWF)is a multimeric plasma glycoprotein that captures platelets to the sites of vascular injury.The adhesive activity of VWF is highly dependent on the size of VWF.Hemodynamic force converts coiled VWF to linear form,exposing the scissile bond Y1605-M1606 within A2 domain.ADAMTS13(A Disintegrin and Metalloprotease with a ThromboSpondin type 1 motif 13)inhibits excessive platelet aggregation by specifically cleaving the cryptic peptide bond of VWF to regulate its size.Deficiency of ADAMTS13 activity,caused by either mutations or by inhibitory autoantibody,results in the accumulation of ultra-large VWF in plasma,leading to excessive platelet aggregation and disseminated VWF/plateletrich thrombus formation,which is the characteristic of thrombotic thrombocytopenic purpura(TTP).Previous studies showed that,circulating ADAMTS13 generally adopts a closed conformation by the interaction of its TSP8-CUB domain and Spacer domain.This auto-inhibition is relieved when VWF D4-CK domain binds to C-termini of ADAMTS13 disrupting the interaction between TSP8-CUB domain and Spacer domain.As a result,ADAMTS13 changes into an open conformation,exposing more VWF binding sites.Open conformation of ADAMTS13 is considered as a hallmark of acute acquired TTP.However,the dynamic process of conformational transition of ADAMTS13 has not been fully understood.Besides,there are variable natural truncations of ADAMTS13 in circulation,including the truncations lacking the metalloprotease domain.The role of these truncations without enzyme activity in hemostasis is still unknown.Given that there are multiple binding sites in both VWF and open ADAMTS13,we hypothesize that open ADAMTS13 promotes the cross-linking of VWF.Atomic force microscopy(AFM)was employed to prove our hypothesis at single molecule level.The N-termini of ADAMTS13 was immobilized on the polystyrene surface,while the C-termini was stretched by AFM tip.The force required for unfolding was measured and the molecular length increment was obtained by fitting the data with worm-like chain model.In addition,both the polystyrene surface and cantilever were coated with VWF,the adhesion frequency of VWF-VWF interaction were measured in the presence or absence of soluble DisC(a ADAMTS13 truncation that lacks the metalloprotease domain).Our results show that,the rupture force required for ADAMTS13 unfolding is^22 pN.The length increment is mainly in the range of 0-50 nm,and the peak value is 22.6±1.8 nm,consistent with the predicted value of homologous modeling(~27 nm)in literature.The adhesion frequency of two VWF molecules increased in the presence of DisC in a concentration-dependent manner.With or without DisC in solution,the rupture force of the VWF molecules was^20 pN.The bond lifetime of two VWF declined with force increasing,the characteristic of a'slip'bond.In contrast,in the presence of DisC,the bond lifetime firstly increased as force increasing and then decreased as force increasing further,which is the characteristic of a'catch-slip'bond.The distinct patterns of bond lifetime vs force in the presence and absence of DisC indicate that DisC promotes the cross-linking of two VWF molecules.Our data suggest that open ADAMTS13 stabilizes the network of VWF multimers and promotes platelet adhesion.

Application of AHP and DTOPSIS in Sugarcane Breeding

The weights of ten important traits of sugarcane, including the number of hair groups, plant height, defoliation capability, stalk diameter, ratooning property, stalk number of disease resistance, cane yield, sucrose content and sugar yield, were distributed with the Analytic Hierarchy Process （AHP） method. Ten Yuetang series of sugarcane lines were evaluated by Dynamic Technique for Order Preference by Similarity to Ideal Solution （DTOPSIS）. AHP results indicated that the weights of ten traits were 0. 013 4, 0.022 7, O. 030 2, 0.040 8, 0.065 3, 0.088 1, 0.116 2, 0. 160 6, 0.198 4 and 0.264 5, respectively, with random consistency ratio C.R. =0.098 1 〈0.1, suggesting that the distribution of the weights of evaluation indicators was reasonable. Comprehensive evaluation of 10 sugarcane lines by DTOPSLS method combining with the conclusion of AHP showed that the comprehensive performances of Yuetang 03-393 and Yuetang 03-373 were much better than other sugarcane lines, with relative approach degree Ci ranking the first and second, respectively, which was basically consistent with the practical survey, suggesting that Yuetang 03-393 and Yuetang 03-373 were suitable for large-scale popularization. The above results confirmed the feasibility of applying AHP and DTOPSIS in comprehensive evaluation of new crop varieties and provided reference for the breeding of new sugarcane lines.

Effect of 30% Tiange Multifunctional Pesticide-Fertilizer on Sugarcane Pests and Yield

In order to study the effect of 30% Tiange multifunctional pesticide-fertilizer on sugarcane pests and sugarcane yield,the field test was conducted with conventional compound fertilizer and 3% carbofuran fertilizer granules as control. The results showed that 30% Tiange multifunctional pesticide-fertilizer could effectively suppress some pests such as sugarcane borer,thrip,aphid and cockchafer. 90 d after pesticide-fertilizer application,the sugarcane withered heart rate was 1. 55% and 2. 55% in the two test points,respectively,significantly lower than the rate of 15. 40% and 19. 40% under control. Before harvest,the sugarcane borer damage rate in the two test points under pesticide-fertilizer treatment was 8. 70% and 9. 47%,respectively,significantly lower than the rate of 34. 50% and 33. 50% under control,and the sugarcane yield was 21. 16% and 22. 14% higher than under control,respectively. 30% Tiange multifunctional pesticide-fertilizer had nutritional and insecticidal effect,which could help to achieve sugarcane pesticide-fertilizer integration and save labor and costs.

Advances in Studies of Genetic Improvement of Sugarcane

Sugarcane(Saccharum spp.) is a large perennial herbaceous plant that is cultivated in tropical and subtropical regions of the world,and it is also one of the most efficient crops in the world in converting energy from sunlight into chemical energy. As an essential sugar crop and energy crop,sugarcane is receiving an increasing concern for its variety improvement. Traditional breeding and cultivation techniques have contributed a lot to increasing sugarcane yield and sucrose content. In recent years,development and application of biotechnology provide much help for genetic improvement of sugarcane. For convenience of breeders fully knowing advances in studies of sugarcane genetic improvement,this paper elaborated conventional breeding,genomics,GM technology,and molecular marker assisted breeding.

Stability and Hopf bifurcation of a delayed virus infection model with latently infected cells and Beddington-DeAngelis incidence

In this paper,the dynamical behaviors for a five-dimensional virus infection model with Latently Infected Cells and Beddington-DeAngelis incidence are investigated.In the model,four delays which denote the latently infected delay,the intracel-lular delay,virus production period and CTL response delay are considered.We define the basic reproductive number and the CTL immune reproductive number.By using Lyapunov functionals,LaSalle's invariance principle and linearization method,the threshold conditions on the stability of each equilibrium are established.It is proved that when the basic reproductive number is less than or equal to unity,the infection-free equilibrium is globally asy mptot ically stable;when the CTL immune repro-ductive number is less than or equal to unity and the basic reproductive number is greater than unity,the immune free infection equilibrium is globally asymptotically stable;when the CTL immune reproductive number is greater than unity and immune response delay is equal to zero,the immune infection equilibrium is globally asymptotically stable.The results show that immune response delay may destabilize the steady state of infection and lead to Hopf bifurcation.The existence of the Hopf bifurcation is discussed by using immune response delay as a bifurcation parameter.Numerical simulations are carried out to justify the analytical results.