Involvement of Protein cAMP‐dependent Kinase,Phospholipase A2 and Phospholipase C in Sperm Acrosome Reaction of Chinchilla lanigera

The mechanisms involved in fertilization are the centre of attention in order to determine the conditions required to reproduce in vitro the events that take place in vivo, with special interest in endangered species. Previous data from mouse sperm, where acrosome reaction (AR) occurs more often in the interstitium of the cumulus oophorus, contribute to strengthen the use of progesterone as a physiological inducer of this process. We studied the participation of protein kinase A (PKA), phospholipases A₂ and C (PLA₂, PLC) in the AR induced by progesterone from Chinchilla epididymal spermatozoa. The addition of db‐cAMP to the incubation medium caused an increase of 58% in the AR, while the use of H89 (30 μm ), a PKA inhibitor, reflected a decrease of 40% in the percentage of reacted gametes. The assays conducted with arachidonic acid showed a maximum increase of 23% in the AR. When gametes were pre‐incubated with PLA₂ inhibitors, a dose‐dependent inhibitory effect was observed. The addition of phorbol12‐myristate13‐acetate (10 μm ) revealed higher percentages of AR induction (60%). When PLC was inhibited with neomycin and U73122, a dose‐dependent decrease in AR percentages was observed. Combined inhibition of PKA, PLA₂ and PLC, AR values similar to control were obtained. This work shows evidence, for the first time in Chinchilla, that progesterone activates the AC/cAMP/PKA system as well as sperm phospholipases and that these signalling pathways participate jointly and cooperatively in AR. These results contribute to the understanding of the complex regulation that is triggered in sperm after the effect of progesterone.     

中欧城市林业规划与管理政策比较

欧洲实践证明, 有效制定和实施林业政策能够推动城市林业的发展, 从而有效改善城市人居环境和促进居民身心健康。文中在收集关于中国和欧洲城市林业方面的文献以及对中国和欧洲进行城市林业实地考察的基础上, 对中国和欧洲城市林业政策与规划、城市林业管理手段、发展城市林业的工作方法进行了比较, 目的是吸收欧洲在城市林业政策制定和实施过程中的先进经验和最佳实践, 提高中国城市林业的政府决策者、管理人员、研究人员、利益相关者和社区在城市林业政策制定和实施方面的知识和能力, 改善中国城市和城市周边地区的环境质量, 最大限度发挥城市林业促进居民身心健康和福祉的作用。     

Tetraploid Wheat—A Resource for Genetic Improvement of Durum Wheat Quality

The tetraploid relatives (subspecies) of commercial durum wheat (Triticum turgidum L. subsp. turgidum conv. durum (Desf.) MacKey) offer a source of economically useful genes for the genetic improvement of durum cultivars. Tetraploid wheat subspecies show a wide diversity in grain protein composition and content, which are major factors determining the pasta-making quality of durum cultivars. In this study, the specific focus was the identification of accessions expressing one or more superior pasta-making traits. In all, 33 accessions were surveyed representing five different subspecies; var. durum (13 accessions), polonicum (7 accessions), persicum (3 accessions), turanicum (6 accessions), and turgidum (4 accessions). These accessions and the durum cultivars Wollaroi and Kamilaroi (in both years) and Yallaroi (in 1998 only) were grown at Tamworth, Australia in 1997 and 1998. Grain, semolina, and spaghetti cooking quality were evaluated using a range of tests. Several accessions were identified with larger grain size and protein content and higher semolina extraction. Although many of the accessions were weaker in dough strength, a few were equal to the commercial cultivars and produced pasta of comparable quality. The main disadvantage with these accessions was the low yellow color. These quality defects can be corrected by conventional breeding.