The fertilization process is the net result of a complex sequence of events that collectively result in the fusion of theopposite gametes. The male gamete undergoes continuous morphological and biochemical modificatio...The fertilization process is the net result of a complex sequence of events that collectively result in the fusion of theopposite gametes. The male gamete undergoes continuous morphological and biochemical modifications during spermdevelopment in the testis (spermatogenesis), maturation in the epididymis, and capacitation in the female reproductivetract. Only the capacitated spermatozoa are able to recognize and bind to the bioactive glycan residue(s) on the ovum'sextracellular coat, the zona pellucida (ZP). Sperm-zona binding in the mouse and several other species is believed totake place in two stages. First, capacitated (acrosome-intact) spermatozoa loosely and reversibly adhere to the zona-in-tact ovum. In the second stage tight irreversible binding occurs. Both types of bindings are attributed to the presence ofglycan- binding proteins (receptors) on the sperm plasma membrane and their complementary bioactive glycan units(ligands) on the surface of the ZP. The carbohydrate-mediated adhesion event initiates a signal transduction cascade re-sulting in the exocytosis of acrosomal contents. This step is believed to be prerequisite which allows the hyperactivatedacrosome-reacted spermatozoa to penetrate the ZP and fertilize the ovum. This review focuses on the role of carbohy-drate residues in sperm-ovum interaction, and triggering of the acrosome reaction. I have attempted to discuss extensiveprogress that has been made to enhance our understanding of the well programmed multiple molecular events necessaryfor successful fertilization. This review will identify these events, and discuss the functional significance of carbohy-drates in these events.展开更多
The Cemitério Palaeolake deposit in Catalao, Goiás State, Brazil, comprises a single, complete lacustrine sequence, dated from less than 27,500 ± 4000 yr B.P. to more than 51,780 ± 400 14C yr B.P. ...The Cemitério Palaeolake deposit in Catalao, Goiás State, Brazil, comprises a single, complete lacustrine sequence, dated from less than 27,500 ± 4000 yr B.P. to more than 51,780 ± 400 14C yr B.P. The unprecedented presence of spongillite and diatomite layers in this deposit was investigated using spicules of continental sponges as proxy data for environmental and climate reconstruction, which was relatively extensive for the ages examined. From the analysis of the sedimentary features and the associations of spicules preserved in the deposit, it was possible to reconstruct the evolution of the limnic system. Five developmental stages were thus identified, corresponding to the installation (lotic and erosion phase), establishment and development of the lake and its colmatation, the latter correlating to the Last Glacial Maximum (LGM). Moreover, based on the ecological requirements of the sponge species identified in the deposit, it was possible to infer the likely weather patterns related to respective phases of the lake. The presence of the sponge species Corvoheteromeyenia australis, presently recorded only from southern South America, indicated that polar incursions originating from the Antarctic were frequent during the last glacial period and might have played a notable role in what is now central Brazil. However, for a short time, drier and hotter weather conditions might have predominated, as suggested by the presence of the species Corvomeyenia thumi.展开更多
The cross section values of the^(71)Ga(n,γ)^(72)Ga reaction are measured,which are 9.14±0.81 mb and 5.74±0.50 mb at 2.15 and 3.19 MeV,respectively.The detailed uncertainty propagation and covariance analysi...The cross section values of the^(71)Ga(n,γ)^(72)Ga reaction are measured,which are 9.14±0.81 mb and 5.74±0.50 mb at 2.15 and 3.19 MeV,respectively.The detailed uncertainty propagation and covariance analysis are also given.The^(7)Li(p,n)^(7)Be reaction was used to generate the neutrons,and the neutron flux was normalized using the^(115)In(n,n′)^(115)In^(m)monitor reaction.The measured cross section data are compared with the data available in the EXFOR database,the data obtained using nuclear reaction model codes EMPIRE-3.2 and TALYS-1.95,and also the evaluated nuclear data from ENDF/B-VIII.0 and JEFF-3.1/A.The comparison shows that our result at 3.19 MeV is in good agreement with those of EMPIRE-3.2 and JEFF-3.1/A.Since there are no other measurements available at3.19 MeV,our data could not be compared with literature data at 3.19 MeV,but they are consistent with the cross section values available at 2.98±0.26 and 3.0±0.1 MeV.Our result at 2.15 MeV is slightly higher than the literature value available in EXFOR,evaluated value,and theoretically predicted result.展开更多
基金The work was supported in part by grants HD25869 and HD34041 from the National Institute of Child & Human Development
文摘The fertilization process is the net result of a complex sequence of events that collectively result in the fusion of theopposite gametes. The male gamete undergoes continuous morphological and biochemical modifications during spermdevelopment in the testis (spermatogenesis), maturation in the epididymis, and capacitation in the female reproductivetract. Only the capacitated spermatozoa are able to recognize and bind to the bioactive glycan residue(s) on the ovum'sextracellular coat, the zona pellucida (ZP). Sperm-zona binding in the mouse and several other species is believed totake place in two stages. First, capacitated (acrosome-intact) spermatozoa loosely and reversibly adhere to the zona-in-tact ovum. In the second stage tight irreversible binding occurs. Both types of bindings are attributed to the presence ofglycan- binding proteins (receptors) on the sperm plasma membrane and their complementary bioactive glycan units(ligands) on the surface of the ZP. The carbohydrate-mediated adhesion event initiates a signal transduction cascade re-sulting in the exocytosis of acrosomal contents. This step is believed to be prerequisite which allows the hyperactivatedacrosome-reacted spermatozoa to penetrate the ZP and fertilize the ovum. This review focuses on the role of carbohy-drate residues in sperm-ovum interaction, and triggering of the acrosome reaction. I have attempted to discuss extensiveprogress that has been made to enhance our understanding of the well programmed multiple molecular events necessaryfor successful fertilization. This review will identify these events, and discuss the functional significance of carbohy-drates in these events.
基金CNPq for granting of the Universal Project(Process 481555/2009-9)R.Iannuzzi acknowledges CNPq for research fellowship granted(Process PQ305687/2010-7 and PQ309211/2013-1).
文摘The Cemitério Palaeolake deposit in Catalao, Goiás State, Brazil, comprises a single, complete lacustrine sequence, dated from less than 27,500 ± 4000 yr B.P. to more than 51,780 ± 400 14C yr B.P. The unprecedented presence of spongillite and diatomite layers in this deposit was investigated using spicules of continental sponges as proxy data for environmental and climate reconstruction, which was relatively extensive for the ages examined. From the analysis of the sedimentary features and the associations of spicules preserved in the deposit, it was possible to reconstruct the evolution of the limnic system. Five developmental stages were thus identified, corresponding to the installation (lotic and erosion phase), establishment and development of the lake and its colmatation, the latter correlating to the Last Glacial Maximum (LGM). Moreover, based on the ecological requirements of the sponge species identified in the deposit, it was possible to infer the likely weather patterns related to respective phases of the lake. The presence of the sponge species Corvoheteromeyenia australis, presently recorded only from southern South America, indicated that polar incursions originating from the Antarctic were frequent during the last glacial period and might have played a notable role in what is now central Brazil. However, for a short time, drier and hotter weather conditions might have predominated, as suggested by the presence of the species Corvomeyenia thumi.
基金Under the financial assistance of the B.R.N.S.,DAE,Mumbai(Sanction No.2012/36/17-BRNS Dated 14.08.2012),this research was carried out as part of a collaborative research project between the Department of Physics,Mizoram University and BARC,Mumbaithe grants received from the Institutions of Eminence(IoE)BHU(6031-B)UGC-DAE Consortium for Scientific Research(CRS/2021-22/02/474)
文摘The cross section values of the^(71)Ga(n,γ)^(72)Ga reaction are measured,which are 9.14±0.81 mb and 5.74±0.50 mb at 2.15 and 3.19 MeV,respectively.The detailed uncertainty propagation and covariance analysis are also given.The^(7)Li(p,n)^(7)Be reaction was used to generate the neutrons,and the neutron flux was normalized using the^(115)In(n,n′)^(115)In^(m)monitor reaction.The measured cross section data are compared with the data available in the EXFOR database,the data obtained using nuclear reaction model codes EMPIRE-3.2 and TALYS-1.95,and also the evaluated nuclear data from ENDF/B-VIII.0 and JEFF-3.1/A.The comparison shows that our result at 3.19 MeV is in good agreement with those of EMPIRE-3.2 and JEFF-3.1/A.Since there are no other measurements available at3.19 MeV,our data could not be compared with literature data at 3.19 MeV,but they are consistent with the cross section values available at 2.98±0.26 and 3.0±0.1 MeV.Our result at 2.15 MeV is slightly higher than the literature value available in EXFOR,evaluated value,and theoretically predicted result.
